CVE-2026-121949: sensiolabs symfony · Incomplete List of Disallowed Inputs
Affects sensiolabs symfonySource CVE Database V5
Not known to be exploited · CVSS 2.3 Low · fixed in 8.1.11 : update sensiolabs symfony when convenient.
Data as of 5 Nov 2026, 18:05 UTC
Thin evidence
One scorer or none| CNA (Checkmarx) | CVSS 4.0 | 2.3 |
|---|
- Patch
- Available – fixed in 8.1.11, 7.4.23, 6.4.50
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 5 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.
What to do
Upgrade symfony and symfony/html-sanitizer to 8.1.11, 7.4.23 or 6.4.50.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| symfonysymfony/html-sanitizer | Affected
| Fixed in
|
| symfonysymfony/html-sanitizer | Affected
| Fixed in
|
| symfonysymfony/html-sanitizer | Affected
| Fixed in
|
Packagistsymfony/html-sanitizerpkg:composer/symfony/html-sanitizerOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Upgrade Symfony HtmlSanitizer to version 6.4.50, 7.4.23, or 8.1.11 or later, where this issue is fixed. These versions properly validate URLs in srcset and imagesrcset attributes according to the configured media schemes and hosts allowlists. No other mitigation is required if the upgrade is applied.
Description
Symfony HtmlSanitizer versions prior to 6.4.50, 7.4.23, and 8.1.11 do not properly validate URLs in the srcset and imagesrcset attributes, allowing disallowed hosts or schemes to bypass media URL policies. This can cause browsers to load images from untrusted sources, potentially enabling user tracking or IP logging without authentication.