CVE-2026-109399
SWUpdate through 2026.05.1 CMS Signature Verification Bypass via Embedded Intermediates
sbabic swupdate
CVSS
9.2CriticalExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.21%Chance of exploitation activity in the next 30 days, higher than 10% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed inNone listedNo source names a fixed version. Check the vendor advisory below
What fixes it
No source in this snapshot names a fixed version. The vendor advisories under References are the place to check.
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.
Text from CVE List
Affected versions 1
- swupdateaffected: all versions through 2026.05.1CVE List
References 5
- github.com/sbabic/swupdate/commit/e66c5640664a31668926a24c0c84b6b6570dc0d9Fixvia CVE List
- vulncheck.com/advisories/swupdate-through-2026.05.1-cms-signature-verification-bypass-via-embedded-intermediatesAdvisoryvia CVE List
- groups.google.com/g/swupdate/c/dsoMcGFnEnsReferencevia CVE List
- github.com/sbabic/swupdate/blob/2026.05.1/crypto/swupdate_cms_verify_openssl.cReferencevia CVE List
- github.com/sbabic/swupdateReferencevia CVE List