Bug 2552544

Summary: CVE-2026-77696 openssl3: OpenSSL: Private key recovery via SM2 timing side-channel [epel-all]
Product: [Fedora] Fedora EPEL Reporter: Srikanth Balasubramanian <sbalasub>
Component: openssl3Assignee: Robert Scheck <redhat-bugzilla>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: epel10CC: dbelyavs, redhat-bugzilla
Target Milestone: ---Keywords: Security, SecurityTracking
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Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["04341cbe-2731-4934-9962-967e12886380"]}
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On:    
Bug Blocks: 2543258    

Description Srikanth Balasubramanian 2026-10-14 17:18:08 UTC 
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

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.