CVE-2026-101903

Description

Axios is a promise-based HTTP client for the browser and Node.js. From 1.16.1 until 1.20.0, the RFC 2397 regular expression allows slash characters on both sides of the media-type separator. An application passes an attacker-controlled malformed data URL containing many slash characters and no comma. the JavaScript regular-expression engine explores many separator placements before rejecting the URL. Synchronous excessive backtracking can block the Node.js event loop and cause denial of service. The affected identifiers are fromDataURI, DATA_URL_PATTERN, data:. This issue is fixed in version 1.20.0.

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Weakness Type (CWE)

CWE-1333 CWE-1333

References

Other References

https://github.com/axios/axios/commit/d19040bda7a8be2f82c3c6e1a5bc03917daee39a https://github.com/axios/axios/pull/11141 https://github.com/axios/axios/releases/tag/v1.20.0 https://github.com/axios/axios/security/advisories/GHSA-c29m-xwm3-cm6r https://github.com/axios/axios/security/advisories/GHSA-c29m-xwm3-cm6r

Frequently Asked Questions

What is CVE-2026-101903? +

Axios is a promise-based HTTP client for the browser and Node.js. From 1.16.1 until 1.20.0, the RFC 2397 regular expression allows slash characters on both sides of the media-type separator. An application passes an attacker-controlled malformed data URL containing many slash characters and no comma. the JavaScript regular-expression engine explores many separator placements before rejecting the URL. Synchronous excessive backtracking can block the Node.js event loop and cause denial of service. The affected identifiers are fromDataURI, DATA_URL_PATTERN, data:. This issue is fixed in version 1.20.0.

How do I check if I'm vulnerable to CVE-2026-101903? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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