# CVE-2026-63475: isomorphic-git: Circular symbolic references cause non-terminating resolution (DoS)

Status: published. Published: 2026-11-03. Updated: 2026-11-03.

isomorphic-git is a pure JavaScript implementation of Git for Node.js and browsers. Prior to 1.38.6, isomorphic-git persists server-supplied circular symref= capabilities through updateRemoteRefs, and GitRefManager.resolve() follows the resulting loose symbolic references without a default depth limit or cycle detection. After a clone from a malicious or man-in-the-middle-controlled remote, operations such as log, status, checkout, and branch that resolve refs/remotes/origin/a or refs/remotes/origin/b do not terminate. The circular references remain on disk, leaving the repository unusable for the application and causing a persistent denial of service. This issue is fixed in version 1.38.6.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- isomorphic-git / isomorphic-git: < 1.38.6 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 4.3 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-674, CWE-835

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/isomorphic-git/isomorphic-git/security/advisories/GHSA-96wc-2m84-2cj7 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/isomorphic-git/isomorphic-git/pull/2370 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/isomorphic-git/isomorphic-git/commit/823843d1cd19182df79bc907c767f5bcecb39a0b (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/isomorphic-git/isomorphic-git/releases/tag/v1.38.6 (CNA: GitHub_M; x_refsource_MISC)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-63475; retrieved 2026-11-03; source updated 2026-11-03

Revision: 23cfef357892276ca69aec584f8190a7c5fe5141fdb80de92916ea17b7c54ec6

Canonical: https://y2.dev/cve/CVE-2026-63475

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