# CVE-2025-62517: Rollbar prototype pollution in merge()

Source: https://junglewise.ai/threats/cve-2025-62517-rollbar-prototype-pollution-in-merge  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-10-23. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2025-62517 · Severity: medium · CVSS 5.9 · Published 2025-10-23

Rollbar is a popular JavaScript error tracking and logging library used by applications to monitor crashes and errors in production. A prototype pollution vulnerability in the merge() function allows attackers to modify JavaScript object prototypes if untrusted data is passed to rollbar.configure(). This could lead to unexpected behavior, property injection, or application compromise depending on how the poisoned objects are used downstream.

Technologies: [rollbar (npm)](https://junglewise.ai/threats/technologies/rollbar). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2025-62517 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-62517 being exploited in the wild.

**How severe is CVE-2025-62517?** Medium severity, with a CVSS score of 5.9, published 23 October 2025.

**Which products and versions are affected?** rollbar (npm) SEMVER:introduced=0,fixed=2.26.5.

**Is there a fix for CVE-2025-62517?** Yes. rollbar (npm): upgrade to 2.26.5 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2025-62517 attacked?** It is attacked over the network.

**Am I affected by CVE-2025-62517?** Check whether you run rollbar (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

- rollbar (npm): upgrade to 2.26.5 or later

  ```sh
  npm install rollbar@2.26.5
  ```


## Technical details

The vulnerability is a prototype pollution flaw (CWE-1321) in the merge() function of the Rollbar JavaScript library. An attacker can exploit this by crafting untrusted input containing special properties (e.g., "__proto__" or "constructor.prototype") that get passed to rollbar.configure(). No authentication or user interaction is required; the attack vector is network-based with high attack complexity. The impact is limited to integrity violations through property poisoning rather than confidentiality or availability breaches. Patches are available in versions 2.26.5 and 3.0.0-beta5.

## Affected products

- Rollbar rollbar <=2.26.4, >=3.0.0-alpha1 and <=3.0.0-beta4

## Identifiers

- CVE-2025-62517
- GHSA-xcg2-9pp4-j82x

## Timeline

- 2025-10-23: disclosed
- 2025-10-23: patched: Fixed in versions 2.26.5 and 3.0.0-beta5

## References

- [https://github.com/rollbar/rollbar.js/security/advisories/GHSA-xcg2-9pp4-j82x](https://github.com/rollbar/rollbar.js/security/advisories/GHSA-xcg2-9pp4-j82x)

## Related threats

- [Rollbar prototype pollution in utility function](https://junglewise.ai/threats/cve-2025-57325-rollbar-prototype-pollution-in-utility-function)
- [Rollbar prototype pollution in utility.set](https://junglewise.ai/threats/rollbar-prototype-pollution-in-utility-set-627ea302)