CVE record · CVE-2026-121949

Symfony: HtmlSanitizer Does Not URL-Sanitize srcset and imagesrcset: Media Scheme and Host Allow-List Bypass

CVSS 2.3 Low

Published by the CVE Program (CNA: Checkmarx) at 5 Nov 2026, 17:46 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
sensiolabs	symfony Package name: symfony/html-sanitizer https://packagist.org/packages/symfony/html-sanitizer	affected 6.1.0 to before 6.4.50 git affected 7.0.0 to before 7.4.23 git affected 8.0.0 to before 8.1.11 git Other versions: unaffected

Identifiers: CVE-2026-121949
CNA: Checkmarx
Weakness (CWE): CWE-184 · CWE-1023
Tags: sensiolabs symfony
CWE-184
CWE-1023
Published: 5 Nov 2026
Updated: 5 Nov 2026

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
2.3	Low	4.0	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N	CNA (Checkmarx)Used for this record
5.4	Medium	3.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N	ADP (CISA-ADP)

CISA KEV Not listed.
EPSS No score.

Timeline

5 Nov 2026, 17:46 UTC Confirmed by the CVE List
5 Nov 2026, 17:54 UTC First seen by agentprime
5 Nov 2026, 18:17 UTC Confirmed by NVD

Sources

References from the CNA

github.com/symfony/symfony/security/advisories/GHSA-q8jq-xrf4-v5j8 third-party-advisory
github.com/symfony/symfony/commit/50e7a38a8f088601c09669b9d267c9c0228884e1 patch

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.