CVE-2026-42077: Evolver prototype pollution in mailbox store via Object.assign()

CVE-2026-42077 · Severity: medium · CVSS 5.2 · Published 2026-05-04

Evolver is an AI agent framework that includes a mailbox module for storing messages. A prototype pollution vulnerability in the mailbox store allows attackers with write access to the message persistence file to inject malicious properties that affect all JavaScript objects in the application, potentially enabling authentication bypass or logic manipulation.

Technologies: EvoMap Evolver, @evomap/evolver (npm). Vendors: EvoMap, npm.

Quick answers

Is CVE-2026-42077 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-42077 being exploited in the wild.
How severe is CVE-2026-42077?
Medium severity, with a CVSS score of 5.2, published 4 May 2026.
Which products and versions are affected?
EvoMap Evolver < 1.69.3; @evomap/evolver (npm) SEMVER:introduced=0,fixed=1.69.3.
Is there a fix for CVE-2026-42077?
Yes. @evomap/evolver (npm): upgrade to 1.69.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-42077 attacked?
It is attacked with local access, in a software library.
Am I affected by CVE-2026-42077?
Check whether you run EvoMap Evolver or @evomap/evolver (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • @evomap/evolver (npm): upgrade to 1.69.3 or later
    npm install @evomap/evolver@1.69.3

Technical details

The vulnerability is a prototype pollution flaw (CWE-1321) in src/proxy/mailbox/store.js at lines 123 and 145. The _applyUpdate() and _updateRecord() functions use Object.assign() to merge fields read from the messages.jsonl persistence file without filtering dangerous prototype-polluting keys such as __proto__, constructor, or prototype. An attacker with write access to the messages.jsonl file can craft a malicious JSONL entry containing __proto__ as a field key to inject properties into Object.prototype, affecting all JavaScript objects. The attack requires file write access, achievable through file upload vulnerabilities, path traversal, compromised backups, or shared hosting. Once triggered, the polluted prototype can enable authentication bypass, authorization bypass, or application logic manipulation. The vulnerability is fixed in version 1.69.3.

Affected products

  • EvoMap Evolver < 1.69.3

Identifiers

  • CVE-2026-42077
  • GHSA-2cjr-5v3h-v2w4

Timeline

  • 2026-04-22: disclosed
  • 2026-04-20: patched: Fix released in version 1.69.3

References

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