Bug 2552552

Summary:	CVE-2026-77696 sslscan: OpenSSL: Private key recovery via SM2 timing side-channel [epel-all]
Product:	[Fedora] Fedora EPEL	Reporter:	Srikanth Balasubramanian <sbalasub>
Component:	sslscan	Assignee:	Michal Ambroz <rebus>
Status:	NEW ---	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	epel10	CC:	rebus, saroy
Target Milestone:	---	Keywords:	Security, SecurityTracking
Target Release:	---
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:
Embargoed:
Bug Depends On:
Bug Blocks:	2543258

Description Srikanth Balasubramanian 2026-10-14 17:18:49 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.