CVE-2026-89011 isomorphic-git < 1.42.0 Prototype Pollution via getRemoteInfo
A malicious Git server can pollute Object.prototype via crafted ref names, causing credential leakage and network rerouting in isomorphic-git.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-89011?
CVE-2026-89011 is a high-severity unsafe deserialization vulnerability in isomorphic-git, published on 10 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-1321
Which versions are affected by CVE-2026-89011?
How do I fix CVE-2026-89011?
No fix has been published for CVE-2026-89011 yet. Limit exposure of the affected software until one is available.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-89011 being exploited?
There is no known exploitation of CVE-2026-89011 in the wild and no public exploit code.
Sources
Also known as GHSA-83vg-jxvh-fx76.