CVE-2026-109399: SWUpdate through 2026.05.1 CMS Signature Verification Bypass via Embedded Intermediates
SWUpdate through 2026.05.1 contains an improper certificate validation vulnerability in crypto/swupdatecmsverifyopenssl.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.
Affected Software
Event History
Frequently Asked Questions
Which deployments are affected?
SWUpdate versions through 2026.05.1 are affected. The available information does not state whether any particular configuration avoids the issue.
What does an attacker need to exploit this?
The attacker needs a signing key from a sibling intermediate certificate under the same trusted root. They can then include that intermediate in CMS SignedData to have a malicious update accepted.
What is the likely impact if exploitation succeeds?
An attacker can install malicious updates. The reported severity vector rates confidentiality, integrity, and availability impact as high.