Issue summary: A non-constant-time optimized implementation of scalar point multiplication is used for SM2 private key operations on ARM64 and RISC-V platforms.

Impact summary: An attacker able to measure the time taken by, or to observe the cache-line access pattern of SM2 signing or decryption on an affected platform can learn information about the secret scalar.

CWE: CWE-208: Observable Timing Discrepancy

Description: On ARM64 and RISC-V processors, the SM2 curve uses an optimized scalar multiplication implementation whose conditional branches and table look ups are chosen according to the bits of the secret scalar. The execution time and the cache-access pattern therefore depend on the long-term private key (during SM2 decryption) or the per-signature nonce (during SM2 signature generation), forming a timing and cache side-channel.

FIPS Impact: no SM2 is not a FIPS algorithm and the optimized SM2 implementation is not part of the FIPS module.

OpenSSL 4.0, 3.6, 3.5 and 3.4 are vulnerable to this issue on AArch64 and RISC-V.

OpenSSL 3.0, 1.1.1 and 1.0.2 are not affected by this issue.

OpenSSL 4.0 users should upgrade to OpenSSL 4.0.3. OpenSSL 3.6 users should upgrade to OpenSSL 3.6.5. OpenSSL 3.5 users should upgrade to OpenSSL 3.5.9. OpenSSL 3.4 users should upgrade to OpenSSL 3.4.8.

This issue was reported on 2 May 2026 by Abhinav Agarwal. It was independently reported on 6 June 2026 by Feng Xue. The fix was developed by Igor Ustinov.

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Issue summary: A non-constant-time optimized implementation of scalar point multiplication is used for SM2 private key operations on ARM64 and RISC-V platforms.

Impact summary: An attacker able to measure the time taken by, or to observe the cache-line access pattern of SM2 signing or decryption on an affected platform can learn information about the secret scalar.

CWE: CWE-208: Observable Timing Discrepancy

Description: On ARM64 and RISC-V processors, the SM2 curve uses an optimized scalar multiplication implementation whose conditional branches and table look ups are chosen according to the bits of the secret scalar. The execution time and the cache-access pattern therefore depend on the long-term private key (during SM2 decryption) or the per-signature nonce (during SM2 signature generation), forming a timing and cache side-channel.

FIPS Impact: no SM2 is not a FIPS algorithm and the optimized SM2 implementation is not part of the FIPS module.

OpenSSL 4.0, 3.6, 3.5 and 3.4 are vulnerable to this issue on AArch64 and RISC-V.

OpenSSL 3.0, 1.1.1 and 1.0.2 are not affected by this issue.

OpenSSL 4.0 users should upgrade to OpenSSL 4.0.3. OpenSSL 3.6 users should upgrade to OpenSSL 3.6.5. OpenSSL 3.5 users should upgrade to OpenSSL 3.5.9. OpenSSL 3.4 users should upgrade to OpenSSL 3.4.8.

This issue was reported on 2 May 2026 by Abhinav Agarwal. It was independently reported on 6 June 2026 by Feng Xue. The fix was developed by Igor Ustinov.

-- cut (non-publishing meta…

openssl: openssl: Denial of Service via excessive memory allocation in CRL distribution point processing openssl: openssl: Traffic amplification Denial of Service via QUIC packet over-accounting openssl: openssl: Denial of Service via inefficient QUIC stream reassembly openssl: OpenSSL: Private key recovery via timing side-channel in generic elliptic curve operations openssl: openssl: Denial of Service via excessive QUIC packet buffer retention openssl: openssl: information disclosure via non-constant-time SM2 scalar multiplication on ARM64 and RISC-V openssl: openssl: Denial of Service via out-of-bounds write during TLS context switch openssl: OpenSSL: Denial of Service via unenforced QUIC connection flow control openssl: openssl: Denial of Service via crafted CMP certificate revocation response openssl: OpenSSL: Denial of Service via undersized DTLS record openssl: OpenSSL: Private key recovery via SM2 timing side-channel openssl: compat-openssl: openssl: Information disclosure via DTLS handshake retransmission openssl: OpenSSL: Denial of Service via unbounded QUIC connection identifier backlog

Affected: Ubuntu:Pro:22.04:LTS: nodejs, Ubuntu:26.04:LTS: edk2, Ubuntu:26.04:LTS: edk2-hwe, Ubuntu:26.04:LTS: openssl

Issue summary: A non-constant-time optimized implementation of scalar point multiplication is used for SM2 private key operations on ARM64 and RISC-V platforms. Impact summary: An attacker able to measure the time taken by, or to observe the cache-line access pattern of SM2 signing or decryption on an affected platform can learn information about the secret scalar. CWE: CWE-208: Observable Timing Discrepancy Description: On ARM64 and RISC-V processors, the SM2 curve uses an optimized scalar multiplication implementation whose conditional branches and table look ups are chosen according to the bits of the secret scalar. The execution time and the cache-access pattern therefore depend on the long-term private key (during SM2 decryption) or the per-signature nonce (during SM2 signature generation), forming a timing and cache side-channel. FIPS Impact: no SM2 is not a FIPS algorithm and the optimized SM2 implementation is not part of the FIPS module. OpenSSL 4.0, 3.6, 3.5 and 3.4 are vulnerable to this issue on AArch64 and RISC-V. OpenSSL 3.0, 1.1.1 and 1.0.2 are not affected by this issue. OpenSSL 4.0 users should upgrade to OpenSSL 4.0.3. OpenSSL 3.6 users should upgrade to OpenSSL 3.6.5. OpenSSL 3.5 users should upgrade to OpenSSL 3.5.9. OpenSSL 3.4 users should upgrade to OpenSSL 3.4.8. This issue was reported on 2 May 2026 by Abhinav Agarwal. It was independently reported on 6 June 2026 by Feng Xue. The fix was developed by Igor Ustinov. -- cut (non-publishing metadata for…