CVE-2026-104845 is a high-severity (CVSS 7.5) CWE-770 vulnerability in seroval. A fix is available for seroval — see the affected versions and patch details below.
Seroval: Memory exhaustion via unchecked TypedArray length in JSON deserialization
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- 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-2026-104845.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-104845 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
serovalReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Summary
deserializeTypedArray casts the source node to ArrayBuffer without checking it and never bounds the element count. Pass a plain object with a length property and it hits the array-like TypedArray constructor, allocating that many elements. The offset guard above it can't stop this: source.byteLength is undefined, so the comparison is always false.
The length is one integer in the JSON, so a tiny payload can name any allocation size, and it runs synchronously inside fromJSON, starving the event loop instead of just slowing one request. fromCrossJSON is the same.
Impact is unauthenticated CPU/memory exhaustion for any service deserializing untrusted Seroval JSON: same profile as the array-length and nested-depth DoS issues already fixed here. No confidentiality or integrity impact. DataView has the same unchecked cast but throws instead of allocating. A runtime instanceof ArrayBuffer check plus a size cap should fix it.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | seroval | all versions | 1.6.3npm install seroval@1.6.3 |
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 1.6.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-104845 is resolved across your whole dependency graph.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.
Frequently Asked Questions
Is CVE-2026-104845 in your dependencies?
Find it across npm, including transitive dependencies.