high · 7.5 Patched

Seroval: fromJSON deserializer trusts node-supplied array length and sequence doneAt (unauthenticated event-loop DoS)

CVE-2026-116581 · GHSA-97r2-qh9m-474h · published 28 Oct 2026

How serious is it

  • Severity: high, CVSS score 7.5 out of 10.
  • No exploit prediction (EPSS) score yet.
  • Not on the CISA list of exploited vulnerabilities.
  • No public exploit in Exploit-DB.

Is your app affected by CVE-2026-116581?

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Who is affected

  • seroval (npm) <= 1.6.7

How to check

  1. Run npm ls seroval in your project to see the installed version, including copies pulled in by other packages.
  2. Or paste your lockfile into the checker: it lists every package with a known vulnerability, this one included.
  3. Or run npx shippable-dev scan localhost:3000 in your project folder. It reads your lockfile and flags this vulnerability along with every other known one.

How to fix

Copies a prompt for Claude Code, Cursor or Codex: it checks your lockfiles for this and upgrades it.
  1. Upgrade seroval to 1.6.8 or later, commit the lockfile and redeploy.
  2. If a vulnerable version was live, check your logs and rotate the secrets that server could read.

The advisory

### 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 `seroval@1.6.8`. - 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.

Check your whole app

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References

Merged from GitHub Advisory Database, OSV. Last updated 29 Oct 2026. All vulnerabilities · RSS · JSON

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