CVE-2026-56017: CWE-476 NULL Pointer Dereference in GTERMARS JavaScript::Minifier::XS
JavaScript::Minifier::XS versions before 0.16 for Perl crash with a NULL pointer dereference when the first meaningful token of the input is a slash. The regexp versus division disambiguator in JsTokenizeString (XS.xs) inspects the previous token's last byte to choose between a regexp literal and a division operator. When a slash is the first meaningful token, with the start of input or only whitespace and comments before it, there is no valid preceding token: the walk back over whitespace and comment nodes runs off the head of the node list to NULL, and the byte lookup reads through a NULL contents pointer at an underflowed length index. The following identifier check dereferences the same NULL pointer. The crash is reachable through the public minify() API, so input as small as a single slash byte crashes the calling process. A service that minifies untrusted or third-party JavaScript can be crashed by a remote request, causing denial of service.
AI Analysis
Technical Summary
The vulnerability in JavaScript::Minifier::XS (versions <0.16) arises from improper handling of the first meaningful token when it is a slash. The function JsTokenizeString (XS.xs) tries to distinguish between a regexp literal and a division operator by inspecting the last byte of the previous token. If the slash is the first meaningful token, there is no valid preceding token, causing the code to dereference a NULL pointer. This leads to a crash reachable via the public minify() API, enabling remote denial of service by crashing services that minify untrusted JavaScript input.
Potential Impact
An attacker can cause a denial of service by sending specially crafted input containing a leading slash to the minify() API, crashing the process that uses JavaScript::Minifier::XS. This affects any service that processes untrusted or third-party JavaScript through this library, potentially disrupting availability.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, avoid processing untrusted JavaScript input with affected versions of JavaScript::Minifier::XS or implement input validation to reject inputs starting with a slash.
CVE-2026-56017: CWE-476 NULL Pointer Dereference in GTERMARS JavaScript::Minifier::XS
Description
JavaScript::Minifier::XS versions before 0.16 for Perl crash with a NULL pointer dereference when the first meaningful token of the input is a slash. The regexp versus division disambiguator in JsTokenizeString (XS.xs) inspects the previous token's last byte to choose between a regexp literal and a division operator. When a slash is the first meaningful token, with the start of input or only whitespace and comments before it, there is no valid preceding token: the walk back over whitespace and comment nodes runs off the head of the node list to NULL, and the byte lookup reads through a NULL contents pointer at an underflowed length index. The following identifier check dereferences the same NULL pointer. The crash is reachable through the public minify() API, so input as small as a single slash byte crashes the calling process. A service that minifies untrusted or third-party JavaScript can be crashed by a remote request, causing denial of service.
CVSS v3.1
Score 7.5high
Affected software
pkg:github/JavaScript-Minifier-XSRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in JavaScript::Minifier::XS (versions <0.16) arises from improper handling of the first meaningful token when it is a slash. The function JsTokenizeString (XS.xs) tries to distinguish between a regexp literal and a division operator by inspecting the last byte of the previous token. If the slash is the first meaningful token, there is no valid preceding token, causing the code to dereference a NULL pointer. This leads to a crash reachable via the public minify() API, enabling remote denial of service by crashing services that minify untrusted JavaScript input.
Potential Impact
An attacker can cause a denial of service by sending specially crafted input containing a leading slash to the minify() API, crashing the process that uses JavaScript::Minifier::XS. This affects any service that processes untrusted or third-party JavaScript through this library, potentially disrupting availability.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, avoid processing untrusted JavaScript input with affected versions of JavaScript::Minifier::XS or implement input validation to reject inputs starting with a slash.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- CPANSec
- Date Reserved
- 2026-06-18T11:27:09.117Z
- Cvss Version
- null
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a42d3d527e9c7971972d1bd
Added to database: 06/29/2026, 20:21:41 UTC
Last enriched: 06/29/2026, 20:36:33 UTC
Last updated: 08/13/2026, 12:41:11 UTC
Views: 79
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