What’s Vulnerable › Vulnerabilities

CVE-2026-89011: isomorphic-git < 1.42.0 Prototype Pollution via getRemoteInfo

• Severity: high (CVSS 7.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-10 · updated 2026-09-23
• Weakness: CWE-1321

Description

isomorphic-git before 1.42.0 contains a prototype pollution vulnerability in the getRemoteInfo function that allows a malicious Git server operator to pollute Object.prototype by advertising crafted ref names containing '__proto__' path segments during ref negotiation. Attackers controlling a Git server can advertise a specially crafted ref such as '__proto__/corsProxy' to reroute all subsequent network operations through an attacker-controlled proxy, causing isomorphic-git to invoke the victim's onAuth callback and transmit credentials to the attacker when the victim calls getRemoteInfo with an attacker-supplied URL.

Affected products

• isomorphic-git: before 1.42.0 — fixed in 1.42.0

How to fix

Upgrade to a fixed version: isomorphic-git 1.42.0. Check the vendor advisory for mitigations.

References

• https://github.com/isomorphic-git/isomorphic-git/commit/b3db111885230bac9a648e0a2312c65ca66f76eb
• https://github.com/isomorphic-git/isomorphic-git/pull/2426
• https://github.com/isomorphic-git/isomorphic-git/releases/tag/v1.42.0
• https://github.com/isomorphic-git/isomorphic-git/security/advisories/GHSA-83vg-jxvh-fx76
• https://www.vulncheck.com/advisories/isomorphic-git-prototype-pollution-via-getremoteinfo

Get alerted when CVE-2026-89011 or the next vulnerability affects your stack