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.

Read the notes from the security team

Why is this CVE low priority?

OpenSSL developers have rated this issue as being low severity

Learn more about Ubuntu priority

Status

Show unmaintained releases

Package	Ubuntu Release	Status
openssl	26.04 LTS resolute	Fixed 3.5.5-1ubuntu3.6
	24.04 LTS noble	Fixed 3.0.13-0ubuntu3.16
	22.04 LTS jammy	Fixed 3.0.2-0ubuntu1.30
	20.04 LTS focal	Fixed 1.1.1f-1ubuntu2.24+esm6
	18.04 LTS bionic	Fixed 1.1.1-1ubuntu2.1~18.04.23+esm11
	16.04 LTS xenial	Fixed 1.0.2g-1ubuntu4.20+esm19
	14.04 LTS trusty	Fixed 1.0.1f-1ubuntu2.27+esm17
openssl-fips	26.04 LTS resolute	Not in release
	24.04 LTS noble	Not in release
	22.04 LTS jammy	Not in release
openssl1.0	26.04 LTS resolute	Not in release
	24.04 LTS noble	Not in release
	22.04 LTS jammy	Not in release
	18.04 LTS bionic	Fixed 1.0.2n-1ubuntu5.13+esm7
nodejs	26.04 LTS resolute	Not affected
	24.04 LTS noble	Not affected
	22.04 LTS jammy	Vulnerable
	20.04 LTS focal	Not affected
	18.04 LTS bionic	Needs evaluation
	16.04 LTS xenial	Needs evaluation
	14.04 LTS trusty	Not affected
edk2	26.04 LTS resolute	Needs evaluation
	24.04 LTS noble	Needs evaluation
	22.04 LTS jammy	Needs evaluation
	20.04 LTS focal	Needs evaluation
	18.04 LTS bionic	Needs evaluation
	16.04 LTS xenial	Needs evaluation
edk2-hwe	26.04 LTS resolute	Needs evaluation
	24.04 LTS noble	Not in release
	22.04 LTS jammy	Not in release

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Notes

mdeslaur

edk2 in jammy embeds OpenSSL 1.1.1j edk2 in noble embeds OpenSSL 3.0.9 edk2 in resolute embeds OpenSSL 3.5.1 edk2 in stonking embeds OpenSSL 3.5.1 nodejs in jammy embeds OpenSSL 1.1.1m 4.0, 3.6, 3.5, 3.4, 3.0 and 1.1.1 are vulnerable

Severity score breakdown

CVSS version: CVSS v3.0

Base score 3.7 · Low

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	High
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	Low
Integrity impact	None
Availability impact	None

Scores

Parameter	Value
Base score	3.7 · Low
Exploitability score	-
Impact score	-

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

References

Related Ubuntu Security Notices (USN)

USN-8847-1
OpenSSL vulnerabilities
29 September 2026

USN-8847-2
OpenSSL vulnerabilities
29 September 2026