CVE-2026-12590: OpenJS body-parser denial of service via invalid limit configuration

Executive brief

The body-parser library, a widely used component for handling data sent to web applications, contains a flaw where certain invalid configuration settings can accidentally disable security limits. If an application uses an unvalidated or improperly calculated size limit, an attacker could send extremely large amounts of data to the server. This can exhaust the server's memory and processing power, potentially causing the application to crash or become unavailable to legitimate users.

Technical details

A vulnerability exists in body-parser where providing an invalid value (such as NaN or an unparseable string) to the 'limit' option causes the underlying 'bytes.parse()' function to return null. When this occurs, the library silently skips request body size enforcement instead of throwing an error or falling back to a safe default. An attacker can exploit this by sending oversized request bodies to applications with such misconfigurations, leading to resource exhaustion (CWE-770). The issue is fixed in versions 1.20.6 and 2.3.0, which now throw an explicit error during parser construction if an invalid limit is provided.

Affected products

• expressjs body-parser < 1.20.6, >= 2.0.0, < 2.3.0

Timeline

• 2026-07-09: disclosed: NVD publication date
• 2026-07-20: advisory: GitHub Advisory published

References

• https://api.github.com/users/Phillip9587
• https://github.com/Phillip9587
• https://api.github.com/users/Phillip9587/gists%7B/gist_id%7D
• https://api.github.com/users/Phillip9587/repos
• https://avatars.githubusercontent.com/u/17254592?v=4
• https://api.github.com/users/Phillip9587/events%7B/privacy%7D