Bug 2543258 (CVE-2026-77696)

Summary:	CVE-2026-77696 openssl: OpenSSL: Private key recovery via SM2 timing side-channel
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	abarbaro, akhatavk, alizardo, anthomas, aos-team-art-private, asdas, csutherl, dpaolell, ehelms, ggainey, jchui, jclere, jdelft, jhe, jpasqual, jupierce, juwatts, ktsao, lblicha, lgarciaa, mbiarnes, mdellweg, mhulan, nboldt, nmoumoul, oaljalju, ogajduse, osousa, pcreech, pjindal, plodge, ppalepu, ppostler, prdhamdh, psrna, rchan, rhel-process-autobot, sghai, sidsharm, smallamp, suppawar, szappis, tmalecek, vchlup, vlaad, watson-tool-maintainers, zhunting
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in OpenSSL. During SM2 signature generation, variable-time arithmetic operations are performed on secret values, creating an observable timing side-channel. An attacker capable of measuring signature generation times can collect timing data across multiple signing operations, which may allow them to recover the private key.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2552539, 2552544, 2552547, 2552552
Bug Blocks:

Description OSIDB Bzimport 2026-09-29 15:54:49 UTC

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.

Comment 1 errata-xmlrpc 2026-11-11 11:25:08 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:98588 https://access.redhat.com/errata/RHSA-2026:98588

Comment 2 errata-xmlrpc 2026-11-11 12:01:15 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:98484 https://access.redhat.com/errata/RHSA-2026:98484