isomorphic-git < 1.42.0 Prototype Pollution via getRemoteInfo (CVE-2026-89011) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-89011

isomorphic-git < 1.42.0 Prototype Pollution via getRemoteInfo

Answer in brief

CVE-2026-89011 records a Unknown severity vulnerability in isomorphic-git < 1.42.0 Prototype Pollution via getRemoteInfo. The current sources do not mark it as known exploited. The current feed maps isomorphic-git/isomorphic-git (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 10, 2026Updated Sep 10, 2026Source checked Sep 10, 2026First seen by HOL Sep 10, 2026Material review Sep 10, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps isomorphic-git/isomorphic-git (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
isomorphic-git/isomorphic-gitgeneric	>=0 <1.42.0	1.42.0

Recommended response

Check inventory. Check lockfiles and deployed manifests for isomorphic-git/isomorphic-git.
Review the reported fix. Update isomorphic-git/isomorphic-git to 1.42.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 10, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 10, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 10, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.