CVE-2026-109399CWE-295

CVE-2026-109399

High · published October 12, 2026

CVSS v3.1
8.1
EPSS
0%
Percentile
10.6
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
8.1 · HIGH
Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
9.2 · 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
EPSS
0.00210 · 10.6th percentile
Weakness
CWE-295 · Improper Certificate Validation
Published
2026-10-12T20:17Z
References (5)
https://github.com/sbabic/swupdate · [email protected]https://github.com/sbabic/swupdate/blob/2026.05.1/crypto/swupdate_cms_verify_openssl.c · [email protected]https://github.com/sbabic/swupdate/commit/e66c5640664a31668926a24c0c84b6b6570dc0d9 · [email protected]https://groups.google.com/g/swupdate/c/dsoMcGFnEns · [email protected]https://www.vulncheck.com/advisories/swupdate-through-2026.05.1-cms-signature-verification-bypass-via-embedded-intermediates · [email protected]
EPSS history
Timeline
  • 14 OCT 03:27Z
    EPSS moved — → 0%
    epss
  • 12 OCT 15:16Z
    SWUpdate through 2026.05.1 CMS Signature Verification Bypass via Embedded Intermediates
    cvelistv5
  • 12 OCT 15:16Z
    SWUpdate through 2026.05.1 CMS Signature Verification Bypass via Embedded Intermediates
    cvelistv5