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

[ Why it matters ]Priority signals

• Public proof-of-concept exploit exists (CISA SSVC)

[ Description ]Official description

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.

[ Fixes ]Fixes and patches

• enshrined/svg-sanitize 1.0.0Fixed version · GitHub Advisories · composer package enshrined/svg-sanitize: upgrade to 1.0.0 or later (affected <= 0.22.0)

[ Packages ]Affected open-source packages

• enshrined/svg-sanitize composerAffected <= 0.22.0 · fixed in 1.0.0 · GHSA-m9xh-6747-9r6f

[ References ]References

• github.com/darylldoyle/svg-sanitizer/commit/2dff6628314de8519155b7feb218bbe132785757
• github.com/darylldoyle/svg-sanitizer/releases/tag/1.0.0
• github.com/darylldoyle/svg-sanitizer/security/advisories/GHSA-m9xh-6747-9r6f