Bug 2545276 (CVE-2026-104846)

Summary: CVE-2026-104846 seroval: Seroval: `fromJSON()` Promise thenable assimilation invokes plugin-produced callables (bypass of CVE-2026-59940)
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: blitton, mbarnett
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A type confusion vulnerability was found in the seroval npm package. The fromJSON() deserialization function, when processing a fulfilled Promise control node, can pass a plugin-produced callable-bearing thenable to a native ECMAScript Promise resolver. Thenable assimilation then invokes the callable unexpectedly, allowing attacker-controlled JSON to trigger code execution in applications using plugin-capable seroval releases (versions 0.12.0 through 1.6.1). This issue bypasses the Promise resolver type-confusion fix in version 1.5.3 (CVE-2026-59940) because the invocation occurs through native Promise settlement after the referenced value is deserialized.
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Description OSIDB Bzimport 2026-10-02 16:24:51 UTC 
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.