Prototype pollution in isomorphic-git - CVE-2026-89011
Published: November 10, 2026
Vulnerability identifier: #VU164398
CSH Severity: Medium
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-89011
CWE-ID: CWE-1321
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to pollute shared object prototypes, redirect subsequent Git requests, and steal authentication credentials.
The vulnerability exists due to prototype pollution in isomorphic-git's getRemoteInfo when unvalidated server-advertised ref segments traverse inherited properties of plain objects. A remote attacker can advertise "http://attacker/proxy __proto__/corsProxy", induce a victim to query the malicious repository, and issue a 401 challenge through the injected proxy during subsequent requests to capture credentials supplied by onAuth.
Affected software
isomorphic-git
How to mitigate CVE-2026-89011
Install security update from vendor's website.
isomorphic-git - update to 1.42.0