CVE-2026-109399: sbabic swupdate

SWUpdate through 2026.05.1 CMS Signature Verification Bypass via Embedded Intermediates

CVSS 9.2 CriticalCriticalEPSS 0.0021 · 10th percentile

Critical, because:

CVSS score 9.2: 9.0 or more.

Published by the CVE Program (CNA: VulnCheck) at 12 Oct 2026, 15:16 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
Vendor	Product	Versions
sbabic	swupdate pkg:github/sbabic/swupdate	affected 2026.05.1 and earlier custom Other versions: unaffected

Identifiers

CVE-2026-109399

CNA

VulnCheck

Weakness (CWE)

CWE-295

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
9.2	Critical	4.0	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	CNA (VulnCheck)Used for this record
8.1	High	3.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H	CNA (VulnCheck)

CISA KEV Not listed.
EPSS 0.0021, the 10th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the CVE Program, published 12 Oct 2026. New records show when each source confirmed them.

Sources

References from the CNA

groups.google.com/g/swupdate/c/dsoMcGFnEns technical-descriptionmailing-list
github.com/sbabic/swupdate/commit/e66c5640664a31668926a24c0c84b6b6570dc0d9 patch
github.com/sbabic/swupdate/blob/2026.05.1/crypto/swupdate_cms_verify_openssl.c technical-description
github.com/sbabic/swupdate product
www.vulncheck.com/advisories/swupdate-through-2026.05.1-cms-signature-verification-bypass-via-embedded-intermediates third-party-advisory

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.