EUVD-2026-91747
GHSA-p6vx-979v-rg4c
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Unauthenticated attacker-controlled JSON reaches deserialization (AV:N/PR:N/UI:N) and reliably triggers callable invocation (AC:L), yielding code execution with full C/I/A impact.
Primary rating from Vendor (GitHub_M).
CVSS VectorVendor: GitHub_M
Lifecycle Timeline
5DescriptionCVE.org
Seroval facilitates JS value stringification, including complex structures beyond JSON.stringify capabilities. From 0.12.0 until 1.6.2, fromJSON deserialization of a fulfilled Promise control node can pass a plugin-produced callable-bearing thenable to a native Promise resolver. ECMAScript thenable assimilation then invokes the callable unexpectedly, allowing attacker-controlled JSON to trigger code in applications using plugin-capable Seroval releases. This path bypasses the Promise resolver type-confusion remediation in version 1.5.3 for CVE-2026-59940 because the unexpected invocation occurs through native Promise settlement after the referenced value is deserialized. This issue is fixed in version 1.6.2.
AnalysisAI
Deserialization of attacker-controlled JSON in plugin-capable Seroval releases 0.12.0 through 1.6.1 lets a remote unauthenticated attacker cause a plugin-produced callable to be invoked unexpectedly through native Promise settlement, resulting in arbitrary code execution in applications that pass untrusted input to the library's fromJSON path. The root cause is a thenable type-confusion defect (CWE-843) that bypasses the Promise resolver remediation shipped in 1.5.3 for CVE-2026-59940 because the dangerous invocation happens inside the native Promise resolution procedure after deserialization rather than in the resolver itself. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires three specific conditions from the description: (1) the application must run a plugin-capable Seroval release in the vulnerable range 0.12.0 through 1.6.1 (fixed in 1.6.2); (2) the attacker must be able to supply attacker-controlled JSON into the Seroval fromJSON deserialization path, i.e. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | All provided signals point to a genuinely high-severity flaw, but one that is conditional rather than universal. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Upgrade to vendor-released patch Seroval 1.6.2 (and seroval-plugins 1.6.2), which adds the thenable guard in deserializer.ts so that a fulfilled or rejected Promise node whose deserialized value is a thenable raises SerovalMalformedNodeError instead of being handed to the native resolver; see GHSA-p6vx-979v-rg4c and commit f1ffcc96d259f9b5b3d71feb262b58240c90e7b7. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory every application, build artifact, and lockfile for Seroval versions 0.12.0 through 1.6.1 using dependency scanning or 'npm ls seroval' across repositories, and treat any service that passes untrusted input into the library's fromJSON path as the priority set; where Seroval 1.6.2 can be pulled from your registry, begin upgrading immediately, and in the interim block untrusted JSON from reaching that path. …
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Seroval is affected by improperly controlled modification of object prototype attributes (prototype pollution) (CVSS 7.3
Same technique Deserialization
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External POC / Exploit Code
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