body-parser vulnerable to Denial of Service via trailing bytes after a compressed request body

Why it is Amber

• CVSS 7.5 high
• Remotely exploitable without logging in
• On your watchlist: npm

Affected packages

References

• https://cna.openjsf.org/security-advisories.html
• https://github.com/expressjs/body-parser/security/advisories/GHSA-27r3-jxmh-p828
• https://github.com/advisories/GHSA-27r3-jxmh-p828
• https://nvd.nist.gov/vuln/detail/CVE-2026-111181
• https://github.com/expressjs/body-parser/commit/1260c3845f54502a05a87594f09a334786bb34d7
• https://github.com/expressjs/body-parser/commit/f7075eae3a84c3473ab4bf0a777da28db208e916
• https://github.com/expressjs/body-parser/releases/tag/1.20.9
• https://github.com/expressjs/body-parser/releases/tag/v2.4.0
• https://github.com/advisories/GHSA-27r3-jxmh-p828

Original description

body-parser is body parsing middleware for Node.js and Express. In versions before 1.20.9 and in versions from 2.0.0 before 2.4.0, a single request can crash any application using body-parser with default options. When a request carries a Content-Encoding such as gzip, body-parser pipes it into a decompression stream and, after reading the body, leaves that stream with no error listener. A payload of one valid compressed frame followed by trailing bytes decodes and the application responds normally, but the trailing bytes then reach the already-finished decoder, which emits an error that is re-thrown as an uncaught exception and terminates the process. No matching route is required because body parsing runs before routing, so any endpoint that parses a body is affected. The issue is fixed in body-parser 2.4.0 and 1.20.9, and users should upgrade to one of those versions or later. As a workaround, disable request-body inflation (set the body-parser inflate option to false) so encoded requests are rejected before any decompression stream is created.