svg-sanitizer: Mixed-case xlink:HrEf skips the `<use>` nesting-DoS check in Resolver::processReferences

published 2026-10-08 31 d ago modified 2026-10-18 22 d ago also EUVD-2026-101125 , GHSA-m9xh-6747-9r6f

cvss: 6.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 40%
public exploits: 0; none known

svg-sanitizer is a PHP SVG/XML sanitizer. Prior to 1.0.0, Resolver::processReferences() in src/ElementReference/Resolver.php builds the SVG <use> reference graph with a case-sensitive href attribute predicate before cleanHrefAttributes() normalizes mixed-case names. An attacker can provide xlink:HrEf on nested <use> elements so the graph omits those references, after which the sanitizer converts the attribute to canonical xlink:href and returns the live nesting structure without applying the useNestingLimit protection. A consuming application that renders the sanitized SVG can therefore be exposed to the resource exhaustion that control is designed to prevent. This issue is fixed in version 1.0.0.

Patch / fix

fixed in 2 links 2

packagist enshrined/svg-sanitize 1.0.0
svg-sanitizer_project svg-sanitizer 1.0.0

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 22 d ago (2026-10-18)

Exploit prediction

0.47% chance of exploitation in the next 30 days, higher than 40% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/darylldoyle/svg-sanitizer/security/advisories/GHSA-m9xh-6747-9r6f referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
GitHub	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Affected packages

ecosystem	package	affected	fixed in
packagist	enshrined/svg-sanitize	<1.0.0	1.0.0

Affected products

darylldoyle svg-sanitizer

Classification

Weakness

CWE-178 Improper Handling of Case Sensitivity
CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary