Executive brief
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.
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
Timeline
- 2025-10-23: disclosed
- 2025-10-23: patched: Fixed in versions 2.26.5 and 3.0.0-beta5