CVE-2026-116581 is a high-severity (CVSS 7.5) CWE-835 vulnerability in seroval. A fix is available for seroval — see the affected versions and patch details below.
Seroval: fromJSON deserializer trusts sequence doneAt (unauthenticated event-loop DoS)
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-116581 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 396,966 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
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.
serovalnpmDescription
Summary
fromJSON and fromCrossJSON used two node fields without checking them.
- An array node's element list was not checked to be an array. A small payload could set the length the decoder looped over. This part is also tracked in GHSA-wp97-x4hv-qvhp.
- A sequence node's done index was not checked. A crafted value produced an iterator that never finished.
Impact
A service that passes untrusted input to fromJSON or fromCrossJSON can be made unavailable by an unauthenticated request.
- The array case blocks the thread while the decoder runs.
- The sequence case makes any code that reads the resulting iterator to the end run forever.
Patches
Fixed in [email protected].
- Element lists must be arrays.
- A sequence node's throw and done indices must be integers from -1 up to the last element index.
Invalid input throws SerovalMalformedNodeError.
Workarounds
None. Upgrade to 1.6.8.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | seroval | all versions | 1.6.8npm install seroval@1.6.8 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for seroval, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update seroval to 1.6.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-116581 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Frequently Asked Questions
Is CVE-2026-116581 in your dependencies?
Find it across npm, including transitive dependencies.