OESA-2026-2781 (CVE-2026-34180)

Vulnerability from osv_openeuler – Published: 2026-06-24 11:11 – Updated: 2026-08-06 11:11 – Source website
VLAI
Summary
openssl security update
Details

OpenSSL is a robust, commercial-grade, and full-featured toolkit for the Transport Layer Security (TLS) and Secure Sockets Layer (SSL) protocols.

Security Fix(es):

Issue summary: Parsing a crafted DER-encoded ASN.1 structure with a primitive element whose content exceeds 2 gigabytes in length may cause a heap buffer over-read on 64-bit Unix and Unix-like platforms.

Impact summary: The heap buffer over-read may crash the application (Denial of Service) or to load into the decoded ASN.1 object contents of memory beyond the end of the input buffer. More typically such ASN.1 elements would instead be truncated.

An integer truncation in OpenSSL's ASN.1 decoder causes the content length of an ASN.1 primitive element to be mishandled when it exceeds 2 gigabytes. In the worst case the truncated length is treated as a request to scan the binary content for a terminating zero byte, possibly causing OpenSSL to read either less than or beyond the end of the allocated buffer.

Applications that pass attacker-supplied data to d2i_X509(), d2i_PKCS7(), or any other d2i_* decoding function are affected. OpenSSL's own command-line tools are not vulnerable, as data read through the BIO layer is checked before it reaches the affected code. The issue only affects 64-bit Unix and Unix-like platforms; 32-bit platforms and 64-bit Windows are not affected.

The FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-34180)

Issue Summary: Cryptographic Message Services (CMS) processing fails to perform sufficient input validation on the cipher and tag length fields of AuthEnvelopedData containers, leading to various potential compromises.

Impact Summary: Attackers making use of these vulnerabilities may achieve key-equivalent functionality for a given CMS recipient and/or bypass integrity validation for a given message.

In one use case, an attacker may send a CMS message containing AuthEnvelopedData with the cipher specified as a non-AEAD cipher. OpenSSL erroneously allows this selection, and attempts to decrypt and validate the message.

An on-path attacker who captures one legitimate AES-GCM AuthEnvelopedData addressed to the victim can re-emit it with the recipientInfos set left byte-for-byte intact, so the victim's private key still unwraps the genuine CEK (the content-encryption key), but with the inner OID rewritten to AES-256-OFB (Output Feedback Mode, an unauthenticated keystream mode) and with an attacker-chosen IV and ciphertext. The victim initializes AES-256-OFB under the real CEK, never consults the MAC field, and CMS_decrypt() returns success.

If the application under attack responds to the attacker with any indicator showing success or failure of the decryption effort, it is possible for the attacker to use this as an oracle to obtain key equivalent functionality for the CEK used for the chosen recipient of the message.

In another use case, an attacker can reduce the tag length of the chosen AEAD cipher for a given AuthEnvelopedData container to be a single byte long, allowing an attacker to brute force CMS decryption, producing an integrity bypass for applications that trust CMS_decrypt() to reject modified content.

The FIPS modules are not affected by this issue.(CVE-2026-34182)

Issue summary: A specially crafted password-encrypted CMS message can trigger a NULL pointer dereference during CMS decryption.

Impact summary: This NULL pointer dereference leads to an application crash and a Denial of Service.

The CMS PasswordRecipientInfo.keyDerivationAlgorithm field is defined as OPTIONAL in the ASN.1 specification and may therefore be absent in specially crafted inputs. During the password-based CMS decryption the OpenSSL CMS implementation dereferences this field without first checking whether it was present.

An attacker who supplies such a CMS message to an application performing password-based CMS decryption can trigger an application crash, leading to a Denial of Service.

Applications that process password-encrypted CMS messages may be affected.

The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-42766)

Issue summary: An attacker-controlled CMP (Certificate Management Protocol) server could trigger a NULL pointer dereference in a CMP client application.

Impact summary: A NULL pointer dereference causes a crash of the application and a Denial of Service.

An attacker controlling a CMP server (or acting as a man-in-the-middle) could craft a CMP response containing a CRMF (Certificate Request Message Format) CertRepMessage with an EncryptedValue structure where the symmAlg field has an algorithm OID but no parameters field. When the OpenSSL CMP client processes this response, the NULL dereference occurs, causing a crash of the CMP client.

Applications that process untrusted CMP/CRMF messages may be affected.

The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-42767)

Issue summary: When EVP_PKEY_derive_set_peer() is called with a DHX (X9.42) peer key, the peer key is not properly checked for the subgroup membership.

Impact summary: A malicious peer which presents an X9.42 key carrying the victim's p and g parameters, a forged q = r (a small prime factor of the cofactor (p−1)/q_local), and a public value Y of order r can recover the victim's private key after a small number of key exchange attempts.

When EVP_PKEY_derive_set_peer() is called with a DHX (X9.42) peer key, the subgroup membership check Y^q ≡ 1 (mod p) is performed using the peer's own q parameter, not the local key's q. The peer's domain parameters are then matched against the domain parameters of the private key, but the value of q is not compared.

A malicious peer who presents an X9.42 key carrying the victim's p, g, a forged q = r (a small prime factor of the cofactor), and a public value Y of order r passes all checks. The shared secret then takes only r distinct values, leaking priv mod r. Repeating for each small-prime factor of the cofactor and combining via CRT recovers the full private key (Lim–Lee / small-subgroup-confinement attack).

The realistic attack surface is narrow: principally CMP deployments with long-lived RA/CA DHX keys and bespoke enterprise or government applications using X9.42 DHX static keys with interactive protocols and therefore this issue was assigned Low severity.

The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are affected by this issue.(CVE-2026-42770)

Issue summary: When an application drives an AES-OCB context through the public EVP_Cipher() one-shot interface, the application-supplied initialisation vector (IV) is silently discarded.

Impact summary: Every message encrypted under the same key uses the same effective nonce regardless of the IV supplied by the caller, resulting in (key, nonce) reuse and loss of confidentiality. If the same code path is used to compute the authentication tag, the tag depends only on the (key, IV) pair and not on the plaintext or ciphertext, allowing universal forgery of arbitrary ciphertext from a single captured message.

OpenSSL provides two ways to drive a cipher: the documented streaming interface (EVP_CipherUpdate / EVP_CipherFinal_ex) and a lower-level one-shot, EVP_Cipher(), whose documentation explicitly recommends against use by applications in favour of EVP_CipherUpdate() and EVP_CipherFinal_ex(). The OCB provider's streaming handler flushes the application-supplied IV into the OCB context before processing data; the one-shot handler did not. Every call to EVP_Cipher() on an AES-OCB context therefore ran with the all-zero key-derived offset state left by cipher initialisation, regardless of the caller's IV.

If EVP_EncryptFinal_ex() is subsequently used to obtain the authentication tag, the deferred IV setup runs at that point and clears the running checksum that should have been accumulated over the plaintext. The resulting tag is a function of (key, IV) only and verifies against any ciphertext produced under the same (key, IV) pair.

The OpenSSL SSL/TLS implementation is not affected: AES-OCB is not a TLS cipher suite, and libssl does not call EVP_Cipher() in any case. Applications that drive AES-OCB through the documented streaming AEAD API (EVP_CipherUpdate / EVP_CipherFinal_ex) are not affected. Only applications that combine the AES-OCB cipher with the EVP_Cipher() one-shot API are vulnerable.

The FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by this issue, as AES-OCB is outside the OpenSSL FIPS module boundary.(CVE-2026-45445)

Issue summary: The implementations of AES-SIV (RFC 5297) and AES-GCM-SIV (RFC 8452) mishandle the authentication of AAD (Additional Authenticated Data) with an empty ciphertext allowing a forgery of such messages.

Impact summary: An attacker can forge empty messages with arbitrary AAD to the victim's application using these ciphers.

AES-SIV (RFC 5297) and AES-GCM-SIV (RFC 8452) are nonce-misuse-resistant AEAD modes: they accept a key, nonce, optional AAD (bytes that are authenticated but not encrypted), and plaintext, and produces ciphertext plus a 16-byte tag. On decrypt, EVP_DecryptFinal_ex() is documented to return success only if the tag is verified succesfully.

In OpenSSL's provider implementation of these ciphers, the expected tag is computed only when decryption function is invoked with non-empty data. If the caller supplies AAD and then calls EVP_DecryptFinal_ex() without invocation of the ciphertext update, which can happen when the received ciphertext length is zero, the tag is never recalculated and still holds its all-zeros value.

When AES-GCM-SIV is used, an attacker who sends arbitrary AAD, empty ciphertext, and all-zeros tag passes authentication under any key they do not know, single-shot. When AES-SIV is used, for mounting the attack it's necessary for the application to reuse the decryption context without resetting the key.

AES-SIV is implemented since OpenSSL 3.0. AES-GCM-SIV is implemented since OpenSSL 3.2.

No protocols implemented in OpenSSL itself (TLS/CMS/PKCS7/HPKE/QUIC) support either AES-GCM-SIV or AES-SIV. To mount an attack, the applications must implement their own protocol and use the EVP interface. Also they must skip the ciphertext update when a message with an empty ciphertext arrives.

The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as these algorithms are not FIPS approved and the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-45446)

Issue summary: A specially crafted PKCS#7 or S/MIME signed message could trigger a use-after-free during PKCS#7 signature verification.

Impact summary: A use-after-free may result in process crashes, heap corruption, or potentially remote code execution.

When processing a PKCS#7 or S/MIME signed message, if the SignedData digestAlgorithms field is present as an empty ASN.1 SET, OpenSSL may incorrectly free a caller-owned BIO during PKCS7_verify(). A subsequent use of the BIO by the calling application results in a use-after-free condition.

In the common case this occurs when the application later calls BIO_free() on the BIO originally passed to PKCS7_verify(). Depending on allocator behavior and application-specific BIO usage patterns, this may result in a crash or other memory corruption. In some application contexts this may potentially be exploitable for remote code execution.

Applications that process PKCS#7 or S/MIME signed messages using OpenSSL PKCS#7 APIs may be affected. Applications using the CMS APIs for this processing are not affected.

The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-45447)

Issue summary: A signed integer overflow when sizing the destination buffer for Unicode output in ASN1_mbstring_ncopy() can lead to a heap buffer overflow.

Impact summary: A heap buffer overflow may lead to a crash or possibly attacker controlled code execution or other undefined behaviour.

In ASN1_mbstring_copy() and ASN1_mbstring_ncopy() the destination size for Unicode output is computed in a signed int: by left shift of the input character count for BMPSTRING (UTF-16) and UNIVERSALSTRING (UTF-32), and by summing per-character byte counts for UTF8STRING. The calculation overflows when the input reaches around 2^30 characters. In the worst case (UNIVERSALSTRING at 2^30 characters) the size wraps to zero, OPENSSL_malloc(1) is called, and the subsequent character copy writes several gigabytes past the one-byte allocation.

X.509 certificate processing routes through ASN1_STRING_set_by_NID(), whose DIRSTRING_TYPE mask excludes UNIVERSALSTRING and whose per-NID size limits cap the input length; no network protocol or certificate-handling path in OpenSSL exercises the overflow. Triggering the bug requires an application that calls ASN1_mbstring_copy() or ASN1_mbstring_ncopy() directly, or registers a custom string type via ASN1_STRING_TABLE_add(), with attacker-controlled input on the order of half a gigabyte or more. For these reasons this issue was assigned Low severity.

The FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-7383)

Issue summary: When CMS password-based decryption (RFC 3211 / PWRI key unwrap) processes attacker-supplied CMS data, an attacker-chosen stream-mode KEK cipher can trigger a heap out-of-bounds read in kek_unwrap_key().

Impact summary: A heap buffer over-read may trigger a crash which leads to Denial of Service for an application if the input buffer ends at a memory page boundary and the following page is unmapped. There is no information disclosure as the over-read bytes are not revealed to the attacker.

The key unwrapping function performs a check-byte test as specified in the RFC that reads 7 bytes from a heap allocation that is based on the wrapped key length from the message. There is a minimum length check based on the block length of the wrapping cipher. However the cipher is selected from an OID carried in the attacker's PWRI keyEncryptionAlgorithm with no requirement that the cipher be a block cipher. When an attacker selects a stream-mode cipher the guard will be ineffective and the allocated buffer containing the unwrapped key can be too small to fit the check-bytes specified in the RFC and a buffer over-read can happen.

Applications calling CMS_decrypt() or CMS_decrypt_set1_password() (equivalently openssl cms -decrypt -pwri_password ...) on untrusted CMS data are vulnerable to this issue. No password knowledge is required: the over-read happens during the unwrap attempt before any authentication succeeds.

The over-read is limited to a few bytes and is not written to output, so there is no information disclosure. Triggering a crash requires the allocation to border unmapped memory, which is unlikely with the normal allocator.

The FIPS modules are not affected by this issue.(CVE-2026-9076)

Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
References
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{
  "affected": [
    {
      "ecosystem_specific": {
        "aarch64": [
          "openssl-3.0.12-52.oe2403sp1.aarch64.rpm",
          "openssl-debuginfo-3.0.12-52.oe2403sp1.aarch64.rpm",
          "openssl-debugsource-3.0.12-52.oe2403sp1.aarch64.rpm",
          "openssl-devel-3.0.12-52.oe2403sp1.aarch64.rpm",
          "openssl-libs-3.0.12-52.oe2403sp1.aarch64.rpm",
          "openssl-perl-3.0.12-52.oe2403sp1.aarch64.rpm"
        ],
        "noarch": [
          "openssl-help-3.0.12-52.oe2403sp1.noarch.rpm"
        ],
        "src": [
          "openssl-3.0.12-52.oe2403sp1.src.rpm"
        ],
        "x86_64": [
          "openssl-3.0.12-52.oe2403sp1.x86_64.rpm",
          "openssl-debuginfo-3.0.12-52.oe2403sp1.x86_64.rpm",
          "openssl-debugsource-3.0.12-52.oe2403sp1.x86_64.rpm",
          "openssl-devel-3.0.12-52.oe2403sp1.x86_64.rpm",
          "openssl-libs-3.0.12-52.oe2403sp1.x86_64.rpm",
          "openssl-perl-3.0.12-52.oe2403sp1.x86_64.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:24.03-LTS-SP1",
        "name": "openssl",
        "purl": "pkg:rpm/openEuler/openssl\u0026distro=openEuler-24.03-LTS-SP1"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.0.12-52.oe2403sp1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "severity": "Critical"
  },
  "details": "OpenSSL is a robust, commercial-grade, and full-featured toolkit for the Transport Layer Security (TLS) and Secure Sockets Layer (SSL) protocols.\r\n\r\nSecurity Fix(es):\n\nIssue summary: Parsing a crafted DER-encoded ASN.1 structure with a primitive\nelement whose content exceeds 2 gigabytes in length may cause a heap buffer\nover-read on 64-bit Unix and Unix-like platforms.\n\nImpact summary: The heap buffer over-read may crash the application (Denial of\nService) or to load into the decoded ASN.1 object contents of memory beyond the\nend of the input buffer.  More typically such ASN.1 elements would instead be\ntruncated.\n\nAn integer truncation in OpenSSL\u0026apos;s ASN.1 decoder causes the content length of\nan ASN.1 primitive element to be mishandled when it exceeds 2 gigabytes. In the\nworst case the truncated length is treated as a request to scan the binary\ncontent for a terminating zero byte, possibly causing OpenSSL to read either\nless than or beyond the end of the allocated buffer.\n\nApplications that pass attacker-supplied data to d2i_X509(), d2i_PKCS7(), or\nany other d2i_* decoding function are affected. OpenSSL\u0026apos;s own command-line\ntools are not vulnerable, as data read through the BIO layer is checked before\nit reaches the affected code. The issue only affects 64-bit Unix and Unix-like\nplatforms; 32-bit platforms and 64-bit Windows are not affected.\n\nThe FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by this issue,\nas the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-34180)\n\nIssue Summary: Cryptographic Message Services (CMS) processing fails to perform\nsufficient input validation on the cipher and tag length fields of\nAuthEnvelopedData containers, leading to various potential compromises.\n\nImpact Summary: Attackers making use of these vulnerabilities may achieve\nkey-equivalent functionality for a given CMS recipient and/or bypass integrity\nvalidation for a given message.\n\nIn one use case, an attacker may send a CMS message containing\nAuthEnvelopedData with the cipher specified as a non-AEAD cipher.  OpenSSL\nerroneously allows this selection, and attempts to decrypt and validate the\nmessage.\n\nAn on-path attacker who captures one legitimate AES-GCM AuthEnvelopedData\naddressed to the victim can re-emit it with the recipientInfos set left\nbyte-for-byte intact, so the victim\u0026apos;s private key still unwraps the genuine CEK\n(the content-encryption key), but with the inner OID rewritten to AES-256-OFB\n(Output Feedback Mode, an unauthenticated keystream mode) and with an\nattacker-chosen IV and ciphertext. The victim initializes AES-256-OFB under the\nreal CEK, never consults the MAC field, and CMS_decrypt() returns success.\n\nIf the application under attack responds to the attacker with any indicator\nshowing success or failure of the decryption effort, it is possible for the\nattacker to use this as an oracle to obtain key equivalent functionality for the\nCEK used for the chosen recipient of the message.\n\nIn another use case, an attacker can reduce the tag length of the chosen AEAD\ncipher for a given AuthEnvelopedData container to be a single byte long,\nallowing an attacker to brute force CMS decryption, producing an integrity\nbypass for applications that trust CMS_decrypt() to reject modified content.\n\nThe FIPS modules are not affected by this issue.(CVE-2026-34182)\n\nIssue summary: A specially crafted password-encrypted CMS message\ncan trigger a NULL pointer dereference during CMS decryption.\n\nImpact summary: This NULL pointer dereference leads to an application crash\nand a Denial of Service.\n\nThe CMS PasswordRecipientInfo.keyDerivationAlgorithm field is defined as\nOPTIONAL in the ASN.1 specification and may therefore be absent in specially\ncrafted inputs. During the password-based CMS decryption the OpenSSL\nCMS implementation dereferences this field without first checking whether it\nwas present.\n\nAn attacker who supplies such a CMS message to an application performing\npassword-based CMS decryption can trigger an application crash, leading to\na Denial of Service.\n\nApplications that process password-encrypted CMS messages may be affected.\n\nThe FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this\nissue, as the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-42766)\n\nIssue summary: An attacker-controlled CMP (Certificate Management Protocol)\nserver could trigger a NULL pointer dereference in a CMP client application.\n\nImpact summary: A NULL pointer dereference causes a crash of the\napplication and a Denial of Service.\n\nAn attacker controlling a CMP server (or acting as a man-in-the-middle) could\ncraft a CMP response containing a CRMF (Certificate Request Message Format)\nCertRepMessage with an EncryptedValue structure where the symmAlg field\nhas an algorithm OID but no parameters field. When the OpenSSL CMP client\nprocesses this response, the NULL dereference occurs, causing a crash of\nthe CMP client.\n\nApplications that process untrusted CMP/CRMF messages may be affected.\n\nThe FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this\nissue, as the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-42767)\n\nIssue summary: When EVP_PKEY_derive_set_peer() is called with a DHX (X9.42)\npeer key, the peer key is not properly checked for the subgroup membership.\n\nImpact summary: A malicious peer which presents an X9.42 key carrying the\nvictim\u0026apos;s p and g parameters, a forged q = r (a small prime factor of the\ncofactor (p\u22121)/q_local), and a public value Y of order r can recover the\nvictim\u0026apos;s private key after a small number of key exchange attempts.\n\nWhen EVP_PKEY_derive_set_peer() is called with a DHX (X9.42) peer key, the\nsubgroup membership check Y^q \u2261 1 (mod p) is performed using the peer\u0026apos;s\nown q parameter, not the local key\u0026apos;s q. The peer\u0026apos;s domain parameters are\nthen matched against the domain parameters of the private key, but the value\nof q is not compared.\n\nA malicious peer who presents an X9.42 key carrying the victim\u0026apos;s p, g,\na forged q = r (a small prime factor of the cofactor), and a public\nvalue Y of order r passes all checks. The shared secret then takes only\nr distinct values, leaking priv mod r. Repeating for each small-prime\nfactor of the cofactor and combining via CRT recovers the full private\nkey (Lim\u2013Lee / small-subgroup-confinement attack).\n\nThe realistic attack surface is narrow: principally CMP deployments with\nlong-lived RA/CA DHX keys and bespoke enterprise or government applications\nusing X9.42 DHX static keys with interactive protocols and therefore this\nissue was assigned Low severity.\n\nThe FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are affected by this\nissue.(CVE-2026-42770)\n\nIssue summary: When an application drives an AES-OCB context through the\npublic EVP_Cipher() one-shot interface, the application-supplied\ninitialisation vector (IV) is silently discarded.\n\nImpact summary: Every message encrypted under the same key uses the\nsame effective nonce regardless of the IV supplied by the caller,\nresulting in (key, nonce) reuse and loss of confidentiality.  If the\nsame code path is used to compute the authentication tag, the tag\ndepends only on the (key, IV) pair and not on the plaintext or\nciphertext, allowing universal forgery of arbitrary ciphertext from a\nsingle captured message.\n\nOpenSSL provides two ways to drive a cipher: the documented streaming\ninterface (EVP_CipherUpdate / EVP_CipherFinal_ex) and a lower-level\none-shot, EVP_Cipher(), whose documentation explicitly recommends\nagainst use by applications in favour of EVP_CipherUpdate() and\nEVP_CipherFinal_ex().  The OCB provider\u0026apos;s streaming handler flushes\nthe application-supplied IV into the OCB context before processing\ndata; the one-shot handler did not.  Every call to EVP_Cipher() on an\nAES-OCB context therefore ran with the all-zero key-derived offset\nstate left by cipher initialisation, regardless of the caller\u0026apos;s IV.\n\nIf EVP_EncryptFinal_ex() is subsequently used to obtain the\nauthentication tag, the deferred IV setup runs at that point and\nclears the running checksum that should have been accumulated over the\nplaintext.  The resulting tag is a function of (key, IV) only and\nverifies against any ciphertext produced under the same (key, IV)\npair.\n\nThe OpenSSL SSL/TLS implementation is not affected: AES-OCB is not a\nTLS cipher suite, and libssl does not call EVP_Cipher() in any case.\nApplications that drive AES-OCB through the documented streaming AEAD\nAPI (EVP_CipherUpdate / EVP_CipherFinal_ex) are not affected.  Only\napplications that combine the AES-OCB cipher with the EVP_Cipher()\none-shot API are vulnerable.\n\nThe FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by\nthis issue, as AES-OCB is outside the OpenSSL FIPS module boundary.(CVE-2026-45445)\n\nIssue summary: The implementations of AES-SIV (RFC 5297) and AES-GCM-SIV\n(RFC 8452) mishandle the authentication of AAD (Additional Authenticated\nData) with an empty ciphertext allowing a forgery of such messages.\n\nImpact summary: An attacker can forge empty messages with arbitrary AAD\nto the victim\u0026apos;s application using these ciphers.\n\nAES-SIV (RFC 5297) and AES-GCM-SIV (RFC 8452) are nonce-misuse-resistant AEAD\nmodes: they accept a key, nonce, optional AAD (bytes that are authenticated\nbut not encrypted), and plaintext, and produces ciphertext plus a 16-byte\ntag. On decrypt, `EVP_DecryptFinal_ex()` is documented to return success only\nif the tag is verified succesfully.\n\nIn OpenSSL\u0026apos;s provider implementation of these ciphers, the expected tag is\ncomputed only when decryption function is invoked with non-empty data.\nIf the caller supplies AAD and then calls `EVP_DecryptFinal_ex()` without\ninvocation of the ciphertext update, which can happen when the received\nciphertext length is zero, the tag is never recalculated and still holds its\nall-zeros value.\n\nWhen AES-GCM-SIV is used, an attacker who sends arbitrary AAD, empty\nciphertext, and all-zeros tag passes authentication under any key they do not\nknow, single-shot. When AES-SIV is used, for mounting the attack it\u0026apos;s\nnecessary for the application to reuse the decryption context without\nresetting the key.\n\nAES-SIV is implemented since OpenSSL 3.0. AES-GCM-SIV is implemented since\nOpenSSL 3.2.\n\nNo protocols implemented in OpenSSL itself (TLS/CMS/PKCS7/HPKE/QUIC) support\neither AES-GCM-SIV or AES-SIV. To mount an attack, the applications must\nimplement their own protocol and use the EVP interface. Also they must skip the\nciphertext update when a message with an empty ciphertext arrives.\n\nThe FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this\nissue, as these algorithms are not FIPS approved and the affected code is\noutside the OpenSSL FIPS module boundary.(CVE-2026-45446)\n\nIssue summary: A specially crafted PKCS#7 or S/MIME signed message could\ntrigger a use-after-free during PKCS#7 signature verification.\n\nImpact summary: A use-after-free may result in process crashes, heap\ncorruption, or potentially remote code execution.\n\nWhen processing a PKCS#7 or S/MIME signed message, if the SignedData\ndigestAlgorithms field is present as an empty ASN.1 SET, OpenSSL may\nincorrectly free a caller-owned BIO during PKCS7_verify(). A subsequent\nuse of the BIO by the calling application results in a use-after-free\ncondition.\n\nIn the common case this occurs when the application later calls\nBIO_free() on the BIO originally passed to PKCS7_verify(). Depending\non allocator behavior and application-specific BIO usage patterns, this\nmay result in a crash or other memory corruption. In some application\ncontexts this may potentially be exploitable for remote code execution.\n\nApplications that process PKCS#7 or S/MIME signed messages using OpenSSL\nPKCS#7 APIs may be affected. Applications using the CMS APIs for this\nprocessing are not affected.\n\nThe FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this\nissue, as the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-45447)\n\nIssue summary: A signed integer overflow when sizing the destination\nbuffer for Unicode output in ASN1_mbstring_ncopy() can lead to a heap\nbuffer overflow.\n\nImpact summary: A heap buffer overflow may lead to a crash or possibly\nattacker controlled code execution or other undefined behaviour.\n\nIn ASN1_mbstring_copy() and ASN1_mbstring_ncopy() the destination\nsize for Unicode output is computed in a signed int: by left shift\nof the input character count for BMPSTRING (UTF-16) and\nUNIVERSALSTRING (UTF-32), and by summing per-character byte counts\nfor UTF8STRING. The calculation overflows when the input reaches\naround 2^30 characters. In the worst case (UNIVERSALSTRING at 2^30\ncharacters) the size wraps to zero, OPENSSL_malloc(1) is called, and\nthe subsequent character copy writes several gigabytes past the\none-byte allocation.\n\nX.509 certificate processing routes through ASN1_STRING_set_by_NID(),\nwhose DIRSTRING_TYPE mask excludes UNIVERSALSTRING and whose per-NID\nsize limits cap the input length; no network protocol or\ncertificate-handling path in OpenSSL exercises the overflow.\nTriggering the bug requires an application that calls\nASN1_mbstring_copy() or ASN1_mbstring_ncopy() directly, or registers\na custom string type via ASN1_STRING_TABLE_add(), with\nattacker-controlled input on the order of half a gigabyte or more.\nFor these reasons this issue was assigned Low severity.\n\nThe FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by\nthis issue, as the affected code is outside the OpenSSL FIPS module\nboundary.(CVE-2026-7383)\n\nIssue summary: When CMS password-based decryption (RFC 3211 / PWRI key unwrap)\nprocesses attacker-supplied CMS data, an attacker-chosen stream-mode KEK\ncipher can trigger a heap out-of-bounds read in kek_unwrap_key().\n\nImpact summary: A heap buffer over-read may trigger a crash which leads to\nDenial of Service for an application if the input buffer ends at a memory\npage boundary and the following page is unmapped. There is no information\ndisclosure as the over-read bytes are not revealed to the attacker.\n\nThe key unwrapping function performs a check-byte test as specified in the\nRFC that reads 7 bytes from a heap allocation that is based on the wrapped\nkey length from the message. There is a minimum length check based on the\nblock length of the wrapping cipher. However the cipher is selected from\nan OID carried in the attacker\u0026apos;s PWRI keyEncryptionAlgorithm with no\nrequirement that the cipher be a block cipher. When an attacker selects\na stream-mode cipher the guard will be ineffective and the allocated buffer\ncontaining the unwrapped key can be too small to fit the check-bytes\nspecified in the RFC and a buffer over-read can happen.\n\nApplications calling CMS_decrypt() or CMS_decrypt_set1_password()\n(equivalently openssl cms -decrypt -pwri_password ...) on untrusted CMS\ndata are vulnerable to this issue. No password knowledge is required: the\nover-read happens during the unwrap attempt before any authentication\nsucceeds.\n\nThe over-read is limited to a few bytes and is not written to output, so\nthere is no information disclosure. Triggering a crash requires the\nallocation to border unmapped memory, which is unlikely with the normal\nallocator.\n\nThe FIPS modules are not affected by this issue.(CVE-2026-9076)",
  "id": "OESA-2026-2781",
  "modified": "2026-08-06T11:11:42Z",
  "published": "2026-06-24T11:11:42Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2781"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-34180"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-34182"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42766"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42767"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42770"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45445"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45446"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45447"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-7383"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-9076"
    }
  ],
  "schema_version": "1.7.2",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "openssl security update",
  "upstream": [
    "CVE-2026-34180",
    "CVE-2026-34182",
    "CVE-2026-42766",
    "CVE-2026-42767",
    "CVE-2026-42770",
    "CVE-2026-45445",
    "CVE-2026-45446",
    "CVE-2026-45447",
    "CVE-2026-7383",
    "CVE-2026-9076"
  ]
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.