CVE-2026-53586

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 80% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — Patch released this week
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.5Exploit: None knownExposed: 0

A fix is available — apply it.

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.

CVSS v3
6.5
EG Score
6.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity65% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
20%
KEV
Not listed

Published

August 20, 2026

Last Modified

August 21, 2026

Advisory Details (6)

Auto-updated Aug 20, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit, github_release.
github_release Patch Available

libgit2 v1.9.5

Patch available: libgit2/libgit2 v1.9.5

https://github.com/libgit2/libgit2/releases/tag/v1.9.5
github_release Patch Available

libgit2 v1.8.6

Patch available: libgit2/libgit2 v1.8.6

https://github.com/libgit2/libgit2/releases/tag/v1.8.6
github_commit Patch Available

commit c1507abc4464 (libgit2/libgit2)

Patch available: libgit2/libgit2 v1.8.6 (contains commit c1507abc4464)

https://github.com/libgit2/libgit2/commit/c1507abc44647b3acd832a33a5b1c8c9f5ba8821
github_commit Patch Available

commit af2b29ad0a74 (libgit2/libgit2)

Patch available: libgit2/libgit2 v1.9.5 (contains commit af2b29ad0a74)

https://github.com/libgit2/libgit2/commit/af2b29ad0a74d5bac9751376879ddaf848136d3b
github_commit

commit 07de6a7e438f (libgit2/libgit2)

Fix landed in libgit2/libgit2 commit 07de6a7e438f — awaiting tagged release

https://github.com/libgit2/libgit2/commit/07de6a7e438f95ac9a6efd3222a82117e871ed27
github Patch Available🟡 PoC Available

HTTP transport can leak credentials to an offsite redirect target · Advisory · libgit2/libgit2 · GitHub

https://github.com/libgit2/libgit2/security/advisories/GHSA-2889-x8f6-mc4x

Vendor Advisories for CVE-2026-53586(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatlibgit2-main-1.9.7-1.hum12026-08-25redhat
ubuntulibgit2-fixtures (1.1.0+dfsg.1-4.1ubuntu0.1+esm1) @ jammy2026-08-25ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(3)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 21× in last 7d / 21× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-25 18:31 UTCEG score recompute
  2. 2026-08-25 18:31 UTCVendor advisory
  3. 2026-08-25 13:49 UTCEPSS rescore
  4. 2026-08-24 19:29 UTCEG score recompute
  5. 2026-08-24 19:29 UTCVendor advisory
  6. 2026-08-23 20:28 UTCEG score recompute
  7. 2026-08-23 20:28 UTCVendor advisory
  8. 2026-08-23 00:19 UTCEPSS rescore
  9. 2026-08-22 21:27 UTCEG score recompute
  10. 2026-08-22 21:27 UTCVendor advisory
  11. 2026-08-21 23:49 UTCEPSS rescore
  12. 2026-08-21 22:26 UTCEG score recompute
  13. 2026-08-21 22:26 UTCVendor advisory
  14. 2026-08-21 21:54 UTCEG score recompute
  15. 2026-08-21 21:54 UTCVendor advisory
  16. 2026-08-21 18:19 UTCVendor advisory
  17. 2026-08-20 19:18 UTCEG score recompute
  18. 2026-08-20 19:18 UTCVendor advisory
  19. 2026-08-20 18:52 UTCEG score recompute
  20. 2026-08-20 18:52 UTCVendor advisory
  21. 2026-08-20 18:51 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-53586?
CVE-2026-53586 is a medium vulnerability published on August 20, 2026. 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…
When was CVE-2026-53586 disclosed?
CVE-2026-53586 was first published in the National Vulnerability Database on August 20, 2026, with the most recent update on August 21, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-53586 actively exploited?
CVE-2026-53586 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 80.5% of all scored CVEs.
What is the CVSS score of CVE-2026-53586?
CVE-2026-53586 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2026-53586?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-53586, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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