CVE-2026-107379 — enshrined/svg-sanitize: Denial of Service via DTD attribute

What happened

enshrined/svg-sanitize can be made to crash PHP workers when sanitizing a specially crafted SVG DTD. A DTD declaration using a #FIXED attribute default causes the sanitizer code path to call DOMElement::removeAttribute() twice on the same attribute name; the attribute is removed, then the DTD default rematerializes it before a second removal corrupts libxml state and can terminate the PHP worker. An attacker able to submit SVG content to a sanitization endpoint can repeatedly interrupt workers and degrade or exhaust availability. [Sources: 3975,4172,8431,31853]

Technical cause

The sanitizer's cleanAttributesOnWhitelist() path performs two removeAttribute() calls on the same attribute name when a crafted DTD provides a #FIXED attribute default. The first removal deletes the explicit attribute, the DTD default then rematerializes the attribute value, and the second removal corrupts libxml's state, causing the PHP worker to terminate. [Sources: 3975,4172,8431,31853]

Why it matters

Terminating PHP workers via malformed input can be used to degrade or deny service for applications that accept user-supplied SVGs and run the sanitizer synchronously. The vulnerability has a CVSS 3.1 base score of 6.5 (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H), indicating a network-accessible attack path that results in high impact to availability. [Sources: 3975,4172,8431,31853]

Who is affected

Projects and applications that include enshrined/svg-sanitize and expose an endpoint that accepts and sanitizes user-supplied SVG or XML input are affected. The advisory references affected ranges starting at 0 and fixed in 1.0.0; other sources also indicate builds up to and including 0.22.0 are affected. Check your dependency graph for enshrined/svg-sanitize. [Sources: 3975,4172,8431,31853]

Discovery and timeline

Public database entries for this issue were published on 2026-10-08. The package advisory and NVD entries list the vulnerability and remediation. The fact package does not include a discoverer name or a vendor statement beyond the fix; no evidence of exploitation is included. [Sources: 3975,4172,8431,31853]

Affected versions

According to the advisory data, the vulnerability affects enshrined/svg-sanitize from introduced version 0 up to the fixed release 1.0.0. Some registry entries describe affected builds as up to and including 0.22.0. Review your installed version against these ranges. [Sources: 3975,4172,8431,31853]

Fixes and mitigation

A vendor update is available: 1.0.0. Upgrading to that release resolves the double-removal behavior described in the advisory. If you cannot immediately update, consider blocking or sanitizing incoming SVG uploads at a higher level (for example, rejecting SVGs that include DTDs) to avoid processing untrusted DTD declarations. The fact package does not provide additional vendor mitigation guidance. [Sources: 3975,4172,8431,31853]

Recommended action

1) Inspect your dependency tree for enshrined/svg-sanitize and identify services that sanitize user-provided SVG/XML. 2) Upgrade to enshrined/svg-sanitize version 1.0.0. 3) As an interim mitigation, reject or pre-filter SVG inputs that contain DTD declarations before handing them to the sanitizer. 4) Monitor application worker stability and restart policies to reduce impact from unexpected worker termination. [Sources: 3975,4172,8431,31853]