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Fencer Intel
high 7.1

CVE-2026-89011 json

isomorphic-git < 1.42.0 Prototype Pollution via getRemoteInfo

published 2mo ago modified 3d ago also EUVD-2026-75710 , GHSA-83vg-jxvh-fx76

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository isomorphic-git/isomorphic-git. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
7.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits
0
none known

Summary

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.

Patch / fix

  • isomorphic-git isomorphic-git 1.42.0

Is CVE-2026-89011 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-89011 updated cvss 7.1

isomorphic-git: isomorphic-git: Information disclosure via prototype pollution in getRemoteInfo function.

  • Red Hat Ansible Automation Platform 2.1 ansible-automation-platform/automation-portal 1790254963
    fixed: vendor fix RHSA-2026:72712
  • Red Hat Ansible Automation Platform 2.2 ansible-automation-platform/automation-portal 1790256405, ansible-automation-platform/bootc-automation-portal-rhel9 1792641102
    fixed: vendor fix RHSA-2026:72722
  • Red Hat Developer Hub 1.10 rhdh/rhdh-hub-rhel9 1791311495, rhdh/red-hat-developer-hub-backstage-plugin-orchestrator-backend 1791251282, rhdh/red-hat-developer-hub-backstage-plugin-scaffolder-backend-module-orchestrator 1791249640
    fixed: vendor fix RHSA-2026:76788
  • Red Hat Developer Hub 1.10 rhdh/rhdh-rhel9-operator 1791219676, rhdh/rhdh-operator-bundle 1791315788, rhdh/rhdh-must-gather-rhel9 1788278523, rhdh/rhdh-rag-content-rhel9 1791168570, rhdh/red-hat-developer-hub-backstage-plugin-lightspeed 1791242743, rhdh/red-hat-developer-hub-backstage-plugin-orchestrator 1791250003, +3 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
2mo ago

Exploit prediction

0.44% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 4.0 7.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
CNA 3.1 7.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N
CNA 4.0 7.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Inferred packages

No advisory lists a package for this vulnerability yet. The CVE names these as products and links their GitHub repository, and the package registry names the same repository, so they are probably the affected packages. Low confidence: the versions are the CVE’s own for the product, and a stack check reports the package as unchecked when there are none.

ecosystem package repository affected
npm isomorphic-git isomorphic-git/isomorphic-git no versions given

Affected products

  • isomorphic-git isomorphic-git

Classification

Weakness
  • CWE-1321 Improperly Controlled Modification of Object Prototype Attributes

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of isomorphic-git/isomorphic-git published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.