CVE-2026-53586
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.
CSIRTS triage
- What
- Multiple vulnerabilities allow arbitrary command execution on remote SSH servers, credential disclosure, denial of service, and directory creation outside the repository working tree.
- Who is affected
- All deployments of libgit2 using the affected functionality are at risk.
- Urgency
- Urgent; remote code execution on SSH servers is a critical security risk with active exploitation potential.
- Action
- Apply the security update DSA-6453-1 immediately.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.28% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 20% of all EPSS-scored CVEs.
Advisory coverage (3)
- mediumCVE-2026-53586: libgit2 is a portable C implementation of the Git core methods provided as a linkable library …nvd · 2026-08-20
- lowDSA-6453-1 libgit2 - security updatedebian · 2026-08-20
- unknownUSN-8628-1: libgit2 vulnerabilitiesubuntu · 2026-08-12
External references
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