CVE-2026-109399

critical

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.

References

https://www.vulncheck.com/advisories/swupdate-through-2026.05.1-cms-signature-verification-bypass-via-embedded-intermediates

https://groups.google.com/g/swupdate/c/dsoMcGFnEns

https://github.com/sbabic/swupdate/commit/e66c5640664a31668926a24c0c84b6b6570dc0d9

https://github.com/sbabic/swupdate/blob/2026.05.1/crypto/swupdate_cms_verify_openssl.c

https://github.com/sbabic/swupdate

https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-97496

Details

Source: Mitre, NVD

Published: 2026-10-12

Updated: 2026-10-18

Risk Information

CVSS v2

Base Score: 7.6

Vector: CVSS2#AV:N/AC:H/Au:N/C:C/I:C/A:C

Severity: High

CVSS v3

Base Score: 8.1

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Severity: High

CVSS v4

Base Score: 9.2

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

Severity: Critical

EPSS

EPSS: 0.0021