Seroval: Deserialization invokes attacker-chosen callables: AsyncIteratorFactoryInstance calls source.on(listener) without type check

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 rebuilds an AsyncIteratorFactoryInstance by calling source.on(listener) without requiring source to be a genuine internal stream. With untrusted Seroval input and an application plugin that returns a callable value or an object exposing an on method, a crafted node can reuse an identifier so the deserializer invokes the plugin-produced value. This is an incomplete-fix variant of CVE-2026-59940. The resulting confidentiality, integrity, or availability impact depends on the behavior exposed by the application plugin. This issue is fixed in version 1.6.8.

Source published

26 Oct 2026 20:35:49 UTC

Source modified

26 Oct 2026 20:35:49 UTC

Observed here

26 Oct 2026 21:35:30 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Seroval facilitates JavaScript value stringification, including complex structures beyond JSON.stringify capabilities. Prior to 1.6.8, fromJSON rebuilds an AsyncIteratorFactoryInstance by calling source.on(listener) without requiring source to be a genuine internal stream. With untrusted Seroval input and an application plugin that returns a callable value or an object exposing an on method, a crafted node can reuse an identifier so the deserializer invokes the plugin-produced value. This is an incomplete-fix variant of CVE-2026-59940. The resulting confidentiality, integrity, or availability impact depends on the behavior exposed by the application plugin. This issue is fixed in version 1.6.8.

Source published

Oct 26, 2026, 8:35:49 PM (timezone not stated)

Source modified

Oct 26, 2026, 8:35:49 PM (timezone not stated)

Observed here

28 Oct 2026 21:57:35 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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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: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Seroval facilitates JavaScript value stringification, including complex structures beyond JSON.stringify capabilities. Prior to 1.6.8, fromJSON rebuilds an AsyncIteratorFactoryInstance by calling source.on(listener) without requiring source to be a genuine internal stream. With untrusted Seroval input and an application plugin that returns a callable value or an object exposing an on method, a crafted node can reuse an identifier so the deserializer invokes the plugin-produced value. This is an incomplete-fix variant of CVE-2026-59940. The resulting confidentiality, integrity, or availability impact depends on the behavior exposed by the application plugin. This issue is fixed in version 1.6.8.

Source published

26 Oct 2026 21:18:15 UTC

Source modified

26 Oct 2026 21:18:15 UTC

Observed here

28 Oct 2026 21:57:06 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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

### Summary When `fromJSON` rebuilt an async iterator, it called `on()` on the iterator's source without checking that the source was a seroval stream. A crafted payload could pick another value as the source, such as a function returned by an application plugin. The deserializer then called that value's `on` method. This is a variant of GHSA-mv8w-475r-vwqw. That fix covered the promise and stream control nodes but not the async iterator node. ### Impact An application that passes untrusted input to `fromJSON` with plugins that return callable values can have those callables invoked during deserialization. What this allows depends on what the plugin's values do. ### Affected versions - Versions up to 1.6.3 accept any value as the source. - 1.6.4 rejects the reported payload. - 1.6.5 to 1.6.7 check the source by node type, which a payload can get around by reusing a node id. - All versions up to 1.6.7 should be treated as affected. ### Patches Fixed in `[email protected]`. Streams and sequences are now internal class instances. The deserializer checks the source value with `instanceof`, so plain data and plugin values are rejected no matter which node id they use. ### Workarounds Avoid plugins whose `deserialize` returns functions or objects with an `on` method when decoding untrusted input. Upgrading to 1.6.8 is recommended.

Source published

28 Oct 2026 21:17:15 UTC

Source modified

28 Oct 2026 21:30:03 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:L/I:L/A:L

Publisher rating · HIGH