Seroval: Code injection through a typed array's own constructor property

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. From 1.6.0 until 1.6.11, the JavaScript-output APIs derive a typed array's constructor name from a property on the value that can be replaced by an own constructor property. When application code copies untrusted properties onto a typed array and then passes it to serialize, serializeAsync, crossSerialize, crossSerializeAsync, crossSerializeStream, Serializer, or compileJSON, the attacker-controlled name is written as executable JavaScript and can run in the page receiving the output. This issue is fixed in version 1.6.11.

Source published

26 Oct 2026 20:49:35 UTC

Source modified

27 Oct 2026 14:18:01 UTC

Observed here

27 Oct 2026 15:44:06 UTC

Source terms

CVE Program Terms of Use

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: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · 5.3 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

Seroval facilitates JavaScript value stringification, including complex structures beyond JSON.stringify capabilities. From 1.6.0 until 1.6.11, the JavaScript-output APIs derive a typed array's constructor name from a property on the value that can be replaced by an own constructor property. When application code copies untrusted properties onto a typed array and then passes it to serialize, serializeAsync, crossSerialize, crossSerializeAsync, crossSerializeStream, Serializer, or compileJSON, the attacker-controlled name is written as executable JavaScript and can run in the page receiving the output. This issue is fixed in version 1.6.11.

Source published

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

Source modified

Oct 27, 2026, 2:18:01 PM (timezone not stated)

Observed here

28 Oct 2026 21:57:39 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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

EUVD CVSS 4.0 · 5.3 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

Seroval facilitates JavaScript value stringification, including complex structures beyond JSON.stringify capabilities. From 1.6.0 until 1.6.11, the JavaScript-output APIs derive a typed array's constructor name from a property on the value that can be replaced by an own constructor property. When application code copies untrusted properties onto a typed array and then passes it to serialize, serializeAsync, crossSerialize, crossSerializeAsync, crossSerializeStream, Serializer, or compileJSON, the attacker-controlled name is written as executable JavaScript and can run in the page receiving the output. This issue is fixed in version 1.6.11.

Source published

26 Oct 2026 21:18:16 UTC

Source modified

27 Oct 2026 15:16:40 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 4.0 · [email protected] · Secondary · 5.3 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

### Summary seroval writes a typed array as a call to its constructor. In affected versions, the constructor name in the output is read from a property that data on the value can replace, and it is written without checks. A typed array that received properties from untrusted data can then put arbitrary code into the serialized output. ### Details Version 1.6.0 changed how seroval finds the class of an object, so that objects with their own `constructor` property serialize correctly. Typed arrays still took the constructor name from the value itself, so the name could come from the untrusted property instead of the array's real type. These functions are affected: - `serialize`, `serializeAsync` - `crossSerialize`, `crossSerializeAsync`, `crossSerializeStream` - the `Serializer` class - `compileJSON` `fromJSON` and `fromCrossJSON` are not affected: they only accept the names of the built-in typed arrays. With the `compactArrayBufferViews` option, the same lookup throws a `TypeError` instead of writing code. ### Impact An application is affected only when it serializes a typed array that has an own `constructor` property set from untrusted data. That requires code that copies properties from untrusted objects onto a typed array. This is unusual, so the severity is rated Low, even though the result is script execution in the page that receives the output. ### Patches Fixed in 1.6.11. The constructor name now comes from the array's internal type, which properties on the value cannot change. `compactArrayBufferViews` uses the real type as well. ### Workarounds If you cannot upgrade, do not copy properties from untrusted objects onto typed arrays, or remove an own `constructor` property from a typed array before serializing it.

Source published

28 Oct 2026 21:17:36 UTC

Source modified

28 Oct 2026 21:30:05 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_V4 · CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

Publisher rating · MODERATE