Improper Certificate Validation The advisory has been revoked - it doesn't affect any version of package swupdate (opens in a new tab)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIAN13-SWUPDATE-20883322
- published13 Oct 2026
- disclosed12 Oct 2026
Introduced: 12 Oct 2026
NewCVE-2026-109399 (opens in a new tab)Amendment
The Debian security team deemed this advisory irrelevant for Debian:13.
NVD Description
Note: Versions mentioned in the description apply only to the upstream swupdate package and not the swupdate package as distributed by Debian.
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.
References
- https://security-tracker.debian.org/tracker/CVE-2026-109399
- https://github.com/sbabic/swupdate
- https://github.com/sbabic/swupdate/blob/2026.05.1/crypto/swupdate_cms_verify_openssl.c
- https://github.com/sbabic/swupdate/commit/e66c5640664a31668926a24c0c84b6b6570dc0d9
- https://groups.google.com/g/swupdate/c/dsoMcGFnEns
- https://www.vulncheck.com/advisories/swupdate-through-2026.05.1-cms-signature-verification-bypass-via-embedded-intermediates