CVE-2026-12590 is a low-severity (CVSS 3.7) CWE-770 vulnerability in body-parser. A fix is available for body-parser — see the affected versions and patch details below.
body-parser vulnerable to denial of service when invalid limit value silently disables size enforcement
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-12590.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-12590 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
body-parsernpmDescription
Impact
When body-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.
This issue affects applications that pass a programmatically computed or user-configurable value to the limit option without validating it first.
Patches
This issue is fixed in [email protected] and [email protected] via #698. After the fix, invalid limit values throw a clear error at parser construction time instead of silently disabling enforcement. null and undefined continue to fall back to the default limit (100kb).
Workarounds
Validate limit before passing it to body-parser. For example, parse the value with bytes.parse() at startup and reject any configuration where it returns null or a non-finite number.
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | body-parser | all versions | 1.20.6npm install body-parser@1.20.6 |
| 📦npm | body-parser | ≥ 2.0.0&&< 2.3.0 | 2.3.0npm install body-parser@2.3.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for body-parser, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update body-parser to 1.20.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-12590 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-12590 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-12590. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-12590 in your dependencies?
O3 Security finds CVE-2026-12590 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.