CVE-2026-109399

SWUpdate through 2026.05.1 CMS Signature Verification Bypass via Embedded Intermediates

Published Oct 12, 2026 CVSS 4.0 · 9.2 Critical EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4864-1 swupdate security update
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title SWUpdate through 2026.05.1 CMS Signature Verification Bypass via Embedded Intermediates
First Time appeared Swupdate
Swupdate swupdate
Weaknesses CWE-295
CPEs cpe:2.3:a:swupdate:swupdate:*:*:*:*:*:*:*:*
Vendors & Products Swupdate
Swupdate swupdate
References
Metrics cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'}

cvssV4_0

{'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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Oct 18, 2026, 12:03 PM
Reserved
Oct 12, 2026, 2:40 PM
Status
Deferred
Published
Oct 12, 2026, 4:17 PM
Modified
Oct 18, 2026, 12:17 PM