CVE-2026-109399
SWUpdate through 2026.05.1 CMS Signature Verification Bypass via Embedded Intermediates
- State
- Published
- Severity
- 9.2 Critical
- Published
- Oct 12, 2026
- Updated
- Oct 18, 2026
- Reserved
- Oct 12, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 9.2 Critical | 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 | VulnCheck |
| 3.1 | 8.1 High | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H | VulnCheck |
Weaknesses
- CWE-295 Improper Certificate Validation
Affected Products
| Product | Versions |
|---|---|
swupdatesbabic |
|
References
- Researcher Disclosuretechnical-descriptionmailing-list
- https://github.com/sbabic/swupdate/commit/e66c5640664a31668926a24c0c84b6b6570dc0d9patch
- https://github.com/sbabic/swupdate/blob/2026.05.1/crypto/swupdate_cms_verify_openssl.ctechnical-description
- https://github.com/sbabic/swupdateproduct
- VulnCheck Advisory: SWUpdate through 2026.05.1 CMS Signature Verification Bypass via Embedded Intermediatesthird-party-advisory
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