CVE-2026-12590: body-parser vulnerable to denial of service when invalid limit value silently disables size enforcement

Severity: medium (CVSS 5.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-09 · updated 2026-07-10
Weakness: CWE-770

Description

Impact: In body-parser versions prior to 1.20.6 (1.x line) and 2.3.0 (2.x line), when the parser is configured with an invalid limit option value such as an unparseable string or NaN, bytes.parse returns null and the request body size check is silently skipped. Applications that rely on limit as their primary safeguard against oversized request bodies will accept arbitrarily large payloads, leading to excessive memory and CPU usage and denial of service. Patches: This issue is fixed in body-parser 1.20.6 and 2.3.0. After the fix, invalid limit values throw a clear error at parser construction time instead of silently disabling enforcement, while null and undefined continue to fall back to the default limit of 100kb. Workarounds: Validate the limit value before passing it to body-parser. For example, parse the value at startup and reject any configuration where the result is null or a non-finite number.

Affected products

body-parser: before 1.20.6; from 2.0.0 before 2.3.0 — fixed in 1.20.6, 2.3.0
Npm Body-Parser: before 1.20.6; from 2.0.0 before 2.3.0 — fixed in 1.20.6, 2.3.0

How to fix

Upgrade to a fixed version: body-parser 1.20.6, 2.3.0; Npm Body-Parser 1.20.6, 2.3.0. Check the vendor advisory for mitigations.

References

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