Skip to content
Patch Next
Sign inAdd to your agent

← Actionable
Medium, CVSS 4.3amended

isomorphic-git: Circular symbolic references cause non-terminating resolution (DoS)

CVE-2026-63475GHSA-96wc-2m84-2cj7

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (isomorphic-git 1.38.6), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

Add to your agent

Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
4.3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
EPSS
  • CVE-2026-63475: 0.40% estimated exploitation activity in the next 30 days; percentile 34.38 (FIRST EPSS, 2026-11-10). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary A malicious server can advertise circular `symref=` capabilities (e.g. `a → b` and `b → a`). isomorphic-git writes them to disk as loose symrefs, and `GitRefManager.resolve()` follows them with no depth limit and no cycle detection, so any later operation that resolves one of them (`log`, `status`, `checkout`, `branch`, …) loops forever — a persistent denial of service from a single clone.

Details `src/managers/GitRefManager.js` — `resolve()` only enforces a depth limit when a `depth` argument is passed (`depth = undefined` by default), and has no visited-set: ```js static async resolve({ fs, gitdir, ref, depth = undefined }) { if (depth !== undefined) { depth--; if (depth === -1) return ref } … } ``` `updateRemoteRefs` persists all server-supplied symrefs unconditionally. After clone the client has `refs/remotes/origin/a → ref: refs/remotes/origin/b` and `b → a` on disk; resolving either never terminates. Because the bad refs live on disk, the repo is effectively…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from osv record GHSA-96wc-2m84-2cj7

  2. Revision 1 · created ·

    Published from ghsa record GHSA-96wc-2m84-2cj7

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-63475

Advisory: isomorphic-git: Circular symbolic references cause non-terminating resolution (DoS)
IDs: CVE-2026-63475, GHSA-96wc-2m84-2cj7
Record: https://patchnext.com/advisories/cve-2026-63475 (revision 2, source checked 10 Nov 2026, 06:25 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: isomorphic-git 1.38.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm isomorphic-git: affected < 1.38.6; fixed in 1.38.6

## Suggested inspection (read-only)
- `npm ls isomorphic-git --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on isomorphic-git.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-96wc-2m84-2cj7 (GitHub-reviewed advisory GHSA-96wc-2m84-2cj7 lists affected ranges: npm isomorphic-git >=0 <=1.38.5)
- Verified: https://osv.dev/vulnerability/GHSA-96wc-2m84-2cj7 (OSV record GHSA-96wc-2m84-2cj7 lists affected ranges: npm isomorphic-git >=0 <1.38.6 (fixed))

Commands are suggestions: review each one before running it.

Loading voting…