CVE-2026-117541 in svg-sanitizer
Summary
by MITRE • 10/27/2026
svg-sanitizer from 0.11.0 before 1.1.0 contains an uncaught exception vulnerability that allows attackers to crash callers by submitting well-formed XML without a top-level svg root. Attackers can supply documents with a non-svg root or nested svg element, causing Sanitizer::sanitize() to throw a LogicException instead of returning false, crashing workers or bypassing upload rejection.
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Analysis
by VulDB Data Team • 10/27/2026
The vulnerability identified in the svg-sanitizer library versions prior to 1.1.0 represents a critical flaw in input validation and error handling mechanisms within XML parsing routines. Specifically, the issue arises when the sanitizer processes SVG documents that do not conform to expected structural constraints. The core technical failure lies in the Sanitizer::sanitize() method, which is designed to validate incoming SVG content before processing or rendering it. Under normal operational conditions, this function should return a boolean false value if the input fails validation checks, allowing calling applications to gracefully handle rejection of malformed data. However, due to insufficient defensive programming practices, certain edge cases involving well-formed XML structures that lack a top-level svg root element trigger an uncaught LogicException rather than returning the expected error code.
This behavior creates a significant availability risk for systems relying on this library for image processing or content sanitization workflows. When an attacker submits documents featuring non-svg roots or nested svg elements, the internal logic fails to catch the resulting exception. In many server-side environments, particularly those utilizing worker processes such as PHP-FPM or similar asynchronous execution models, uncaught exceptions propagate up the call stack and terminate the current process immediately. This results in a denial of service condition where active workers crash, requiring restarts by the system manager. The impact extends beyond simple downtime; it can lead to resource exhaustion if attackers repeatedly trigger these crashes at scale, overwhelming server capacity or causing cascading failures across dependent services that rely on stable worker availability.
From a security architecture perspective, this flaw aligns with CWE-754: Improper Check for Unusual or Exceptional Conditions and CWE-209: Generation of Error Message Containing Sensitive Information if the exception trace is exposed to users. The failure to handle expected error states gracefully violates fundamental principles of robust software design where input validation must be exhaustive and error paths must be explicitly managed. Furthermore, this vulnerability can facilitate broader attack vectors beyond simple denial of service. By causing worker crashes during upload rejection phases, attackers may bypass security controls that depend on consistent state management or session integrity checks tied to successful request completion. This aligns with ATT&CK technique T1496: Resource Hijacking in the context of availability impact and potentially T1059: Command and Control if the crash leads to unintended side effects in orchestration layers.
Mitigation strategies must prioritize immediate patching to version 1.1.0 or later, where these edge cases are addressed through proper exception handling blocks within the sanitize function. Developers should implement try-catch mechanisms around calls to Sanitizer::sanitize() as a defensive measure until upgrades are deployed. Additionally, input validation layers at the application boundary should enforce strict schema compliance before data reaches the sanitizer library. Logging and monitoring solutions must be configured to detect repeated crashes or exception spikes indicative of exploitation attempts. Regular security audits focusing on error handling paths in third-party libraries will help prevent similar vulnerabilities from impacting system stability and availability.