Seroval: fromJSON deserializer trusts sequence doneAt (unauthenticated event-loop DoS)

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Seroval facilitates JavaScript value stringification, including complex structures beyond JSON.stringify capabilities. Prior to 1.6.8, fromJSON and fromCrossJSON do not validate a sequence node's done index. A crafted done index can create an iterator that never finishes when application code consumes it to completion. An unauthenticated request to a service that deserializes untrusted input can therefore block the event loop, exhaust process memory, or make the service unavailable. This issue is fixed in version 1.6.8.

Source published

26 Oct 2026 20:41:52 UTC

Source modified

26 Oct 2026 20:41:52 UTC

Observed here

26 Oct 2026 21:35:30 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Seroval facilitates JavaScript value stringification, including complex structures beyond JSON.stringify capabilities. Prior to 1.6.8, fromJSON and fromCrossJSON do not validate a sequence node's done index. A crafted done index can create an iterator that never finishes when application code consumes it to completion. An unauthenticated request to a service that deserializes untrusted input can therefore block the event loop, exhaust process memory, or make the service unavailable. This issue is fixed in version 1.6.8.

Source published

Oct 26, 2026, 8:41:52 PM (timezone not stated)

Source modified

Oct 26, 2026, 8:41:52 PM (timezone not stated)

Observed here

28 Oct 2026 21:57:36 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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EUVD CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Seroval facilitates JavaScript value stringification, including complex structures beyond JSON.stringify capabilities. Prior to 1.6.8, fromJSON and fromCrossJSON do not validate a sequence node's done index. A crafted done index can create an iterator that never finishes when application code consumes it to completion. An unauthenticated request to a service that deserializes untrusted input can therefore block the event loop, exhaust process memory, or make the service unavailable. This issue is fixed in version 1.6.8.

Source published

26 Oct 2026 21:18:15 UTC

Source modified

26 Oct 2026 21:18:16 UTC

Observed here

28 Oct 2026 21:57:06 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

### 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.

Source published

28 Oct 2026 21:17:27 UTC

Source modified

28 Oct 2026 21:30:06 UTC

Observed here

28 Oct 2026 21:55:29 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Publisher rating · HIGH