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Fencer Vulns
medium 5.2

CVE-2026-42077 json

Evolver: Prototype Pollution via `Object.assign()` in mailbox store operations

published 2026-04-22 6 mo ago modified 2026-10-26 13 d ago also GHSA-2cjr-5v3h-v2w4 , EUVD-2026-27012

cvss
5.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 4%
public exploits
0
none known

Summary

Evolver is a GEP-powered self-evolving engine for AI agents. Prior to version 1.69.3, a prototype pollution vulnerability in the mailbox store module allows attackers to modify the behavior of all JavaScript objects by injecting malicious properties into Object.prototype. The vulnerability exists in the _applyUpdate() and _updateRecord() functions which use Object.assign() to merge user-controlled data without filtering dangerous keys like __proto__, constructor, or prototype. This issue has been patched in version 1.69.3.

Patch / fix

  • npm @evomap/evolver 1.69.3

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
6 mo ago

Exploit prediction

0.16% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/EvoMap/evolver/security/advisories/GHSA-2cjr-5v3h-v2w4 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.2 CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H
GitHub 3.1 5.2 CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H

Affected packages

ecosystem package affected fixed in
npm @evomap/evolver
<1.69.3
1.69.3

Affected products

  • EvoMap evolver

Classification

Weakness
  • CWE-1321 Improperly Controlled Modification of Object Prototype Attributes

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.