What’s Vulnerable › Vulnerabilities

CVE-2026-104846: Seroval: `fromJSON()` Promise thenable assimilation invokes plugin-produced callables (bypass of CVE-2026-59940)

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-02 · updated 2026-10-05
• Weakness: CWE-843

Description

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.

Affected products

• lxsmnsyc seroval: from 0.12.0, < 1.6.2

References

• https://github.com/lxsmnsyc/seroval/commit/f1ffcc96d259f9b5b3d71feb262b58240c90e7b7
• https://github.com/lxsmnsyc/seroval/security/advisories/GHSA-p6vx-979v-rg4c

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