Advisories

SWUpdate through 2026.05.1 CMS Signature Verification Bypass via Embedded Intermediates

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severity
critical
date
Affecting
  • swupdate <= 2026.05.1

CWE
  • CWE-295 Improper Certificate Validation
CVSS
9.2
CVSS V4 Vector
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Credit
David Gstir (sigma star gmbh), Richard Weinberger (sigma star gmbh)
Description
SWUpdate through 2026.05.1 contains an improper certificate validation vulnerability in crypto/swupdate_cms_verify_openssl.c that trusts untrusted X.509 certificates embedded in CMS SignedData for chain building. Attackers holding a signing key from a sibling intermediate under the same root can embed that intermediate in the signature to install malicious updates.

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