# CVE-2026-53586: libgit2: HTTP transport can leak credentials to an offsite redirect target

> libgit2 leaks HTTP Basic credentials to offsite redirect targets, allowing attackers to steal user credentials via open redirects.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N`)
- **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 available:** Yes
- **Published:** 20 Aug 2026
- **Updated:** 21 Aug 2026
- **Also known as:** AZL-96962, BELL-CVE-2026-53586, DEBIAN-CVE-2026-53586, ECHO-6732-0e6e-c6bd, GHSA-2889-x8f6-mc4x, JLSEC-2026-1372, MINI-h73f-jfh6-j8q5, UBUNTU-CVE-2026-53586, USN-8628-1

## What is CVE-2026-53586?

CVE-2026-53586 is a medium-severity vulnerability in libgit2, published on 20 Aug 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

libgit2 is a portable C implementation of the Git core methods provided as a linkable library with a solid API, allowing to build Git functionality into your application. Prior to 1.8.6 and 1.9.5, the built-in HTTP transport in src/libgit2/transports/http.c follows an offsite initial redirect, and handle_remote_auth and handle_auth pass transport->owner->url instead of transport->server.url to the credential callback when the redirected host returns 401 Unauthorized. A callback that scopes credentials to the original trusted URL can therefore return GIT_CREDENTIAL_USERPASS_PLAINTEXT credentials that libgit2 stores in transport->server.cred and sends as an Authorization header to the redirected host. An attacker who controls a trusted Git host or an open redirect on that host can disclose HTTP Basic credentials, personal access tokens, or equivalent credentials. This issue is fixed in versions 1.8.6 and 1.9.5.

Weakness: CWE-601 (URL Redirection to Untrusted Site), CWE-522 (Insufficiently Protected Credentials), CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2026-53586?


## How do I fix CVE-2026-53586?

Upgrade to a fixed version.

## Is CVE-2026-53586 being exploited?

There is no known exploitation of CVE-2026-53586 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53586 and fix it if it is affected.

What it is: CVE-2026-53586 is a medium-severity vulnerability in libgit2, published on 20 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-53586 in the wild and no public exploit code.

Affected product: libgit2. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-53586/ (Markdown: https://insights.sbomify.com/CVE-2026-53586/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53586
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53586
- OSV: https://osv.dev/vulnerability/CVE-2026-53586

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53586/
Summaries are generated and may contain mistakes; the official description above is the record.