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Fencer Vulns
critical 9.8

CVE-2026-59940 json

Seroval: `seroval.fromJSON()` Promise resolver type confusion invokes attacker-controlled methods during deserialization

published 2026-07-24 3 mo ago modified 2026-10-22 17 d ago also EUVD-2026-60942 , GHSA-mv8w-475r-vwqw

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 57%
public exploits
0
none known

Summary

Seroval facilitates JS value stringification, including complex structures beyond JSON.stringify capabilities. Prior to 1.5.3, seroval.fromJSON() allows attacker-controlled JSON Promise control nodes to operate on values from the general deserialization reference table without verifying genuine internal Promise resolver records, causing deserialization side effects with plugins enabled and potentially unintended server-side invocation or remote code execution when downstream frameworks register callable wrappers. This issue is fixed in version 1.5.3.

Patch / fix

  • npm seroval 1.5.3
  • lxsmnsyc seroval 1.5.3
  • opencode openSUSE Tumbleweed 1.18.26-1.1

opensuse advisories openSUSE-SU-2026:11673-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-59940 updated cvss 9.8

seroval: Seroval: `seroval.fromJSON()` Promise resolver type confusion invokes attacker-controlled methods during deserialization

  • Red Hat Ansible Automation Orchestrator 2026 ansible-automation-platform/automation-orchestrator-ui-rhel9
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
2 mo ago

Exploit prediction

0.81% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
GitHub 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
npm seroval
<1.5.3
1.5.3

Affected products

  • lxsmnsyc seroval

Classification

Weakness
  • CWE-502 Deserialization of Untrusted Data
  • CWE-843 Access of Resource Using Incompatible Type

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.