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.
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
| 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 | Oct 1, 2026 |
| 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 | Oct 1, 2026 |
| libssl1.1 · Ubuntu 20.04 LTS (focal) | 1.1.1f-1ubuntu2.24+esm6 | libssl1.1 1.1.1f-1ubuntu2.24+esm6 | Oct 1, 2026 |
| libssl3 · Ubuntu 22.04.1 LTS (jammy) | 3.0.2-0ubuntu1.30 | libssl3 3.0.2-0ubuntu1.30 | Sep 30, 2026 |
| libssl3t64 · Ubuntu 24.04.5 LTS (noble) | 3.0.13-0ubuntu3.16 | libssl3t64 3.0.13-0ubuntu3.16 | Sep 30, 2026 |
| libssl3t64 · Ubuntu 26.04.1 LTS (resolute) | 3.5.5-1ubuntu3.6 | libssl3t64 3.5.5-1ubuntu3.6 | Sep 28, 2026 |
| openssl · Debian 12.15 (bookworm) | 3.0.22-1~deb12u2 | DEBIAN-CVE-2026-77696 | Sep 30, 2026 |
| openssl · Debian 13.5 (trixie) | 3.5.7-1~deb13u3 | DEBIAN-CVE-2026-77696 | Sep 30, 2026 |
| openssl · Debian 14 | 3.6.5-1 | DEBIAN-CVE-2026-77696 | Sep 30, 2026 |
| 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 | Oct 1, 2026 |
| openssl · Ubuntu 20.04 LTS (focal) | 1.1.1f-1ubuntu2.24+esm6 | openssl 1.1.1f-1ubuntu2.24+esm6 | Oct 1, 2026 |
| openssl · Ubuntu 22.04.1 LTS (jammy) | 3.0.2-0ubuntu1.30 | openssl 3.0.2-0ubuntu1.30 | Sep 30, 2026 |
| openssl · Ubuntu 24.04.5 LTS (noble) | 3.0.13-0ubuntu3.16 | openssl 3.0.13-0ubuntu3.16 | Sep 30, 2026 |
| openssl · Ubuntu 26.04.1 LTS (resolute) | 3.5.5-1ubuntu3.6 | openssl 3.5.5-1ubuntu3.6 | Sep 28, 2026 |
| openssl-3 · opensuse-leap 16.0 | 3.5.0-160000.11.1 | OPENSUSE-SU-2026:22102-1 | Nov 7, 2026 |
| openssl-3 · sles 15.6 | 3.1.4-150600.5.67.1 | SUSE-SU-2026:4419-1 | Oct 2, 2026 |
| openssl-3 · sles 15.7 | 3.5.0-150700.5.53.2 | SUSE-SU-2026:4414-1 | Oct 2, 2026 |
| openssl-3 · sles 16.0 | 3.5.0-160000.11.1 | SUSE-SU-2026:24245-1 | Nov 7, 2026 |
| openssl-provider-legacy · Ubuntu 26.04.1 LTS (resolute) | 3.5.5-1ubuntu3.6 | openssl-provider-legacy 3.5.5-1ubuntu3.6 | Sep 28, 2026 |
| openssl1.0 · Ubuntu 18.04.6 LTS (bionic) | 1.0.2n-1ubuntu5.13+esm7 | openssl1.0 1.0.2n-1ubuntu5.13+esm7 | Oct 1, 2026 |
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