# CVE-2026-77696: Timing Side-Channel in SM2 Signature Generation CVE-2026-77696 is fixed in 8 products on 1 platform, first by libssl3t64 3.5.5-1ubuntu3.6, released September 28, 2026. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2026-77696 - Priority: Routine - CVSS: 3.7 (Low) - EPSS: 0.0040 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Sep 28, 2026 - Weakness: Observable Timing Discrepancy - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-77696 ## Description Issue summary: SM2 signature generation uses non-constant-time arithmetic on secret values, forming a timing side-channel. Impact summary: An attacker able to measure SM2 signing times may learn information about the per-signature secret nonce, which over many signatures can, via a lattice / Hidden Number Problem attack, lead to recovery of the private key. CWE: CWE-208: Observable Timing Discrepancy Description: SM2 signature generation computes the signature value using variable-time BIGNUM operations on the secret nonce and the private key, so the time taken to produce an SM2 signature depends on these secret values, forming a timing side-channel. Applications performing SM2 signature generation are affected on all platforms. FIPS Impact: no SM2 is not a FIPS algorithm. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | libssl1.0.0 Ubuntu 18.04.6 LTS (bionic) | 1.0.2n-1ubuntu5.13+esm7 | [libssl1.0.0 1.0.2n-1ubuntu5.13+esm7](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libssl1.0.0-1.0.2n-1ubuntu5.13-esm7.md) | Oct 1, 2026 | | Linux | libssl1.1 Ubuntu 18.04.6 LTS (bionic) | 1.1.1-1ubuntu2.1~18.04.23+esm11 | [libssl1.1 1.1.1-1ubuntu2.1~18.04.23+esm11](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libssl1.1-1.1.1-1ubuntu2.1-18.04.23-esm11.md) | Oct 1, 2026 | | Linux | libssl1.1 Ubuntu 20.04 LTS (focal) | 1.1.1f-1ubuntu2.24+esm6 | [libssl1.1 1.1.1f-1ubuntu2.24+esm6](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libssl1.1-1.1.1f-1ubuntu2.24-esm6.md) | Oct 1, 2026 | | Linux | libssl3 Ubuntu 22.04.1 LTS (jammy) | 3.0.2-0ubuntu1.30 | [libssl3 3.0.2-0ubuntu1.30](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libssl3-3.0.2-0ubuntu1.30.md) | Sep 30, 2026 | | Linux | libssl3t64 Ubuntu 24.04.5 LTS (noble) | 3.0.13-0ubuntu3.16 | [libssl3t64 3.0.13-0ubuntu3.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libssl3t64-3.0.13-0ubuntu3.16.md) | Sep 30, 2026 | | Linux | libssl3t64 Ubuntu 26.04.1 LTS (resolute) | 3.5.5-1ubuntu3.6 | [libssl3t64 3.5.5-1ubuntu3.6](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libssl3t64-3.5.5-1ubuntu3.6.md) | Sep 28, 2026 | | Linux | openssl Debian 12.15 (bookworm) | 3.0.22-1~deb12u2 | [DEBIAN-CVE-2026-77696](https://patchblox.com/security/data/fix/linux/debian-cve-2026-77696.md) | Sep 30, 2026 | | Linux | openssl Debian 13.5 (trixie) | 3.5.7-1~deb13u3 | [DEBIAN-CVE-2026-77696](https://patchblox.com/security/data/fix/linux/debian-cve-2026-77696.md) | Sep 30, 2026 | | Linux | openssl Debian 14 | 3.6.5-1 | [DEBIAN-CVE-2026-77696](https://patchblox.com/security/data/fix/linux/debian-cve-2026-77696.md) | Sep 30, 2026 | | Linux | openssl Ubuntu 18.04.6 LTS (bionic) | 1.1.1-1ubuntu2.1~18.04.23+esm11 | [openssl 1.1.1-1ubuntu2.1~18.04.23+esm11](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-openssl-1.1.1-1ubuntu2.1-18.04.23-esm11.md) | Oct 1, 2026 | | Linux | openssl Ubuntu 20.04 LTS (focal) | 1.1.1f-1ubuntu2.24+esm6 | [openssl 1.1.1f-1ubuntu2.24+esm6](https://patchblox.com/security/data/fix/linux/ubuntu-focal-openssl-1.1.1f-1ubuntu2.24-esm6.md) | Oct 1, 2026 | | Linux | openssl Ubuntu 22.04.1 LTS (jammy) | 3.0.2-0ubuntu1.30 | [openssl 3.0.2-0ubuntu1.30](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-openssl-3.0.2-0ubuntu1.30.md) | Sep 30, 2026 | | Linux | openssl Ubuntu 24.04.5 LTS (noble) | 3.0.13-0ubuntu3.16 | [openssl 3.0.13-0ubuntu3.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-openssl-3.0.13-0ubuntu3.16.md) | Sep 30, 2026 | | Linux | openssl Ubuntu 26.04.1 LTS (resolute) | 3.5.5-1ubuntu3.6 | [openssl 3.5.5-1ubuntu3.6](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-openssl-3.5.5-1ubuntu3.6.md) | Sep 28, 2026 | | Linux | openssl-3 opensuse-leap 16.0 | 3.5.0-160000.11.1 | [OPENSUSE-SU-2026:22102-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22102-1.md) | Nov 7, 2026 | | Linux | openssl-3 sles 15.6 | 3.1.4-150600.5.67.1 | [SUSE-SU-2026:4419-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4419-1.md) | Oct 2, 2026 | | Linux | openssl-3 sles 15.7 | 3.5.0-150700.5.53.2 | [SUSE-SU-2026:4414-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4414-1.md) | Oct 2, 2026 | | Linux | openssl-3 sles 16.0 | 3.5.0-160000.11.1 | [SUSE-SU-2026:24245-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24245-1.md) | Nov 7, 2026 | | Linux | openssl-provider-legacy Ubuntu 26.04.1 LTS (resolute) | 3.5.5-1ubuntu3.6 | [openssl-provider-legacy 3.5.5-1ubuntu3.6](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-openssl-provider-legacy-3.5.5-1ubuntu3.6.md) | Sep 28, 2026 | | Linux | openssl1.0 Ubuntu 18.04.6 LTS (bionic) | 1.0.2n-1ubuntu5.13+esm7 | [openssl1.0 1.0.2n-1ubuntu5.13+esm7](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-openssl1.0-1.0.2n-1ubuntu5.13-esm7.md) | Oct 1, 2026 | --- Data as of 2026-11-08T06:59:42Z UTC. 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