Vulnerability-Lookup

GHSA-3494-MFXC-798J

Vulnerability from github – Published: 2026-08-27 06:31 – Updated: 2026-08-27 06:31

Details

In the Linux kernel, the following vulnerability has been resolved:

sctp: validate cookie AUTH state before use

When cookie authentication is disabled, COOKIE_ECHO restores fixed-size AUTH fields directly from peer-controlled cookie bytes. A forged RANDOM length, HMAC list, or CHUNKS list can then reach association consumers with lengths or identifiers that were never validated against the local backing arrays.

A forged RANDOM length can cause out-of-bounds reads during key-vector construction. A forged HMAC identifier also caused a 32-byte write past a zero-length AUTH chunk, providing a primitive for a local privilege escalation chain.

Validate the cookie's RANDOM, HMACS, and CHUNKS parameters at the cookie trust boundary before copying them into the association. Reject invalid types, malformed lengths, unsupported HMAC identifiers, HMAC lists without SHA1, and forbidden chunk ids.

Severity

9.8 (Critical)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-74752"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-26T15:16:54Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: validate cookie AUTH state before use\n\nWhen cookie authentication is disabled, COOKIE_ECHO restores fixed-size\nAUTH fields directly from peer-controlled cookie bytes.  A forged RANDOM\nlength, HMAC list, or CHUNKS list can then reach association consumers\nwith lengths or identifiers that were never validated against the local\nbacking arrays.\n\nA forged RANDOM length can cause out-of-bounds reads during key-vector\nconstruction.  A forged HMAC identifier also caused a 32-byte write past\na zero-length AUTH chunk, providing a primitive for a local privilege\nescalation chain.\n\nValidate the cookie\u0027s RANDOM, HMACS, and CHUNKS parameters at the cookie\ntrust boundary before copying them into the association.  Reject invalid\ntypes, malformed lengths, unsupported HMAC identifiers, HMAC lists\nwithout SHA1, and forbidden chunk ids.",
  "id": "GHSA-3494-mfxc-798j",
  "modified": "2026-08-27T06:31:31Z",
  "published": "2026-08-27T06:31:31Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74752"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3dbb44d88b1e94dd31fe43588af7437b34b44d56"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/88619b117be1daf633ce32210570ce35a0bd1c98"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-74752 (GCVE-0-2026-74752)

Vulnerability from cvelistv5 – Published: 2026-08-26 14:36 – Updated: 2026-08-27 05:01

Title

sctp: validate cookie AUTH state before use

Summary

In the Linux kernel, the following vulnerability has been resolved: sctp: validate cookie AUTH state before use When cookie authentication is disabled, COOKIE_ECHO restores fixed-size AUTH fields directly from peer-controlled cookie bytes. A forged RANDOM length, HMAC list, or CHUNKS list can then reach association consumers with lengths or identifiers that were never validated against the local backing arrays. A forged RANDOM length can cause out-of-bounds reads during key-vector construction. A forged HMAC identifier also caused a 32-byte write past a zero-length AUTH chunk, providing a primitive for a local privilege escalation chain. Validate the cookie's RANDOM, HMACS, and CHUNKS parameters at the cookie trust boundary before copying them into the association. Reject invalid types, malformed lengths, unsupported HMAC identifiers, HMAC lists without SHA1, and forbidden chunk ids.

Severity

9.8 (Critical)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

2 references

URL	Tags
https://git.kernel.org/stable/c/88619b117be1daf63…
https://git.kernel.org/stable/c/3dbb44d88b1e94dd3…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 1f485649f52929d9937b346a920a522a7363e202 , < 88619b117be1daf633ce32210570ce35a0bd1c98 (git) Affected: 1f485649f52929d9937b346a920a522a7363e202 , < 3dbb44d88b1e94dd31fe43588af7437b34b44d56 (git)
Linux	Linux	Affected: 2.6.24 Unaffected: 0 , < 2.6.24 (semver) Unaffected: 7.1.10 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/net/sctp/auth.h",
            "net/sctp/auth.c",
            "net/sctp/sm_make_chunk.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "88619b117be1daf633ce32210570ce35a0bd1c98",
              "status": "affected",
              "version": "1f485649f52929d9937b346a920a522a7363e202",
              "versionType": "git"
            },
            {
              "lessThan": "3dbb44d88b1e94dd31fe43588af7437b34b44d56",
              "status": "affected",
              "version": "1f485649f52929d9937b346a920a522a7363e202",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/net/sctp/auth.h",
            "net/sctp/auth.c",
            "net/sctp/sm_make_chunk.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.24"
            },
            {
              "lessThan": "2.6.24",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.10",
                  "versionStartIncluding": "2.6.24",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "2.6.24",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: validate cookie AUTH state before use\n\nWhen cookie authentication is disabled, COOKIE_ECHO restores fixed-size\nAUTH fields directly from peer-controlled cookie bytes.  A forged RANDOM\nlength, HMAC list, or CHUNKS list can then reach association consumers\nwith lengths or identifiers that were never validated against the local\nbacking arrays.\n\nA forged RANDOM length can cause out-of-bounds reads during key-vector\nconstruction.  A forged HMAC identifier also caused a 32-byte write past\na zero-length AUTH chunk, providing a primitive for a local privilege\nescalation chain.\n\nValidate the cookie\u0027s RANDOM, HMACS, and CHUNKS parameters at the cookie\ntrust boundary before copying them into the association.  Reject invalid\ntypes, malformed lengths, unsupported HMAC identifiers, HMAC lists\nwithout SHA1, and forbidden chunk ids."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The bug is reached when a remote peer sends SCTP COOKIE-ECHO to a listening endpoint; packets enter sctp_rcv() and are handled in sctp_sf_do_5_1D_ce()/sctp_unpack_cookie() with no local syscall required on the victim.\nAC:L - With SCTP-AUTH enabled and cookie_hmac_alg=none, an attacker completes INIT/INIT-ACK, forges peer-controlled AUTH fields in the returned cookie, and reliably triggers sctp_auth_make_key_vector()/sctp_auth_calculate_hmac() via COOKIE-ECHO without races or uncontrollable conditions.\nPR:N - Exploitation is pre-authentication SCTP handshake processing on a listening server; the attacker only needs network reachability to the SCTP port and does not need local account privileges, capabilities, or init-namespace root on the target host.\nUI:N - No victim user action is required beyond normal SCTP listener operation; exploitation is achieved solely by sending attacker-crafted COOKIE-ECHO packets over the network during association setup or restart.\nS:U - The vulnerability corrupts kernel memory inside the SCTP stack on the target host and enables kernel privilege escalation; it does not cross a separate security boundary such as guest-to-host VM escape or IOMMU/DMA isolation bypass.\nC:H - A forged RANDOM length copied from an unauthenticated cookie drives sctp_auth_make_key_vector() to memcpy() beyond the fixed auth_random backing array, enabling out-of-bounds kernel memory reads during association shared-key construction.\nI:H - Forged HMAC identifiers from the cookie can yield a zero-length AUTH chunk while sctp_auth_calculate_hmac() still writes a 32-byte digest past the allocation, providing a heap overflow primitive the fix commit notes can chain to local privilege escalation.\nA:H - Out-of-bounds reads and the 32-byte heap overflow during COOKIE-ECHO processing can trigger kernel faults, oops, or panic on SCTP servers, and malformed AUTH state can repeatedly crash association input handling."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-27T05:01:12.709Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/88619b117be1daf633ce32210570ce35a0bd1c98"
        },
        {
          "url": "https://git.kernel.org/stable/c/3dbb44d88b1e94dd31fe43588af7437b34b44d56"
        }
      ],
      "title": "sctp: validate cookie AUTH state before use",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74752",
    "datePublished": "2026-08-26T14:36:59.548Z",
    "dateReserved": "2026-08-15T05:44:03.931Z",
    "dateUpdated": "2026-08-27T05:01:12.709Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

GHSA-3494-MFXC-798J

CVE-2026-74752 (GCVE-0-2026-74752)

Tags

Sightings

Nomenclature