CVE-2026-53583

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: 0.2%, top 91% 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 — 3 sources updated this weekElevated
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: Elevated riskExposed: 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, verify_server_cert in src/libgit2/streams/openssl.c uses an inverted !!memcmp result in the GEN_IPADD branch when comparing an IP-literal host with a certificate IP SubjectAltName. OpenSSL builds reject matching IP addresses and accept mismatched IP addresses, allowing a network attacker with a CA-trusted certificate containing any IP SubjectAltName to intercept libgit2 connections to IP-literal HTTPS URLs. DNS SubjectAltName validation and non-OpenSSL TLS backends are not affected. This issue is fixed in versions 1.8.6 and 1.9.5.

CVSS v3
6.5
EG Score
6.5(medium)
EG Risk
60(Attend)
EG Risk 60/100SSVC: Attend

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%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
9%
KEV
Not listed

Published

August 20, 2026

Last Modified

September 9, 2026

Advisory Details (6)

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

commit ef086bc3e4ee (libgit2/libgit2)

Fix landed in libgit2/libgit2 commit ef086bc3e4ee — awaiting tagged release

https://github.com/libgit2/libgit2/commit/ef086bc3e4eedf62be38a910381aae24d49871ff
github_commit Patch Available

commit c2aa35409ee0 (libgit2/libgit2)

Patch available: libgit2/libgit2 v1.9.5 (contains commit c2aa35409ee0)

https://github.com/libgit2/libgit2/commit/c2aa35409ee0e6515df64da49750f13a0a42c47f
github_commit Patch Available

commit 647dcb432980 (libgit2/libgit2)

Patch available: libgit2/libgit2 v1.8.6 (contains commit 647dcb432980)

https://github.com/libgit2/libgit2/commit/647dcb432980b84ede4cb5a008bbd1ccb4ead03d
github Patch Available🟡 PoC Available

Inverted IP SubjectAltName Comparison in OpenSSL Backend ( vuln_1_1_1 ) · Advisory · libgit2/libgit2 · GitHub

https://github.com/libgit2/libgit2/security/advisories/GHSA-h7gc-w2gg-p9xp

Vendor Advisories for CVE-2026-53583(1)

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

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatlibgit2-main-1.9.7-1.hum12026-08-25redhat

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.

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFixed inDependents
libgit21.5.1+ds-1 ... 1.9.7+ds-1 (32 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
libgit21.9.0+ds-21.9.0+ds-2+deb13u1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
libgit21.9.0+ds-2 ... 1.9.4+ds-1 (13 versions)1.9.6+ds-1—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 16× in last 7d / 71× 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. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 15:14 UTCEG score recompute
  3. 2026-09-18 15:14 UTCVendor advisory
  4. 2026-09-17 13:10 UTCEG score recompute
  5. 2026-09-17 13:10 UTCVendor advisory
  6. 2026-09-16 14:08 UTCEPSS rescore
  7. 2026-09-16 10:46 UTCEG score recompute
  8. 2026-09-16 10:46 UTCVendor advisory
  9. 2026-09-16 05:15 UTCEPSS rescore
  10. 2026-09-15 08:33 UTCEG score recompute
  11. 2026-09-15 08:33 UTCVendor advisory
  12. 2026-09-14 06:29 UTCEG score recompute
  13. 2026-09-14 06:29 UTCVendor advisory
  14. 2026-09-13 16:47 UTCEPSS rescore
  15. 2026-09-13 04:26 UTCEG score recompute
  16. 2026-09-13 04:26 UTCVendor advisory
  17. 2026-09-12 02:22 UTCEG score recompute
  18. 2026-09-12 02:22 UTCVendor advisory
  19. 2026-09-11 14:53 UTCEPSS rescore
  20. 2026-09-11 00:18 UTCEG score recompute
  21. 2026-09-11 00:18 UTCVendor advisory
  22. 2026-09-10 09:35 UTCEPSS rescore
  23. 2026-09-09 21:40 UTCVendor advisory
  24. 2026-09-09 01:55 UTCEG score recompute
  25. 2026-09-09 01:55 UTCVendor advisory
Show 46 more
  1. 2026-09-08 22:01 UTCEPSS rescore
  2. 2026-09-07 16:01 UTCEPSS rescore
  3. 2026-09-07 06:58 UTCEG score recompute
  4. 2026-09-07 06:58 UTCVendor advisory
  5. 2026-09-06 13:47 UTCEPSS rescore
  6. 2026-09-06 04:44 UTCEG score recompute
  7. 2026-09-06 04:44 UTCVendor advisory
  8. 2026-09-05 02:40 UTCEG score recompute
  9. 2026-09-05 02:40 UTCVendor advisory
  10. 2026-09-04 05:06 UTCEPSS rescore
  11. 2026-09-04 00:34 UTCVendor advisory
  12. 2026-09-02 22:27 UTCEG score recompute
  13. 2026-09-02 22:27 UTCVendor advisory
  14. 2026-09-02 14:12 UTCEPSS rescore
  15. 2026-09-01 20:22 UTCEG score recompute
  16. 2026-09-01 20:22 UTCVendor advisory
  17. 2026-09-01 13:54 UTCEPSS rescore
  18. 2026-09-01 04:40 UTCEPSS rescore
  19. 2026-08-31 18:15 UTCEG score recompute
  20. 2026-08-31 18:15 UTCVendor advisory
  21. 2026-08-30 19:17 UTCEPSS rescore
  22. 2026-08-30 13:58 UTCEG score recompute
  23. 2026-08-30 13:58 UTCVendor advisory
  24. 2026-08-30 01:22 UTCEPSS rescore
  25. 2026-08-29 11:54 UTCEG score recompute
  26. 2026-08-29 11:54 UTCVendor advisory
  27. 2026-08-28 21:41 UTCEPSS rescore
  28. 2026-08-28 09:47 UTCEG score recompute
  29. 2026-08-28 09:47 UTCVendor advisory
  30. 2026-08-27 14:25 UTCEPSS rescore
  31. 2026-08-27 07:43 UTCEG score recompute
  32. 2026-08-27 07:43 UTCVendor advisory
  33. 2026-08-26 14:46 UTCEPSS rescore
  34. 2026-08-26 05:39 UTCEG score recompute
  35. 2026-08-26 05:39 UTCVendor advisory
  36. 2026-08-25 13:49 UTCEPSS rescore
  37. 2026-08-25 03:36 UTCEG score recompute
  38. 2026-08-24 01:32 UTCEG score recompute
  39. 2026-08-23 00:19 UTCEPSS rescore
  40. 2026-08-22 23:26 UTCEG score recompute
  41. 2026-08-21 23:49 UTCEPSS rescore
  42. 2026-08-21 21:22 UTCEG score recompute
  43. 2026-08-20 19:18 UTCEG score recompute
  44. 2026-08-20 19:12 UTCEG score recompute
  45. 2026-08-20 18:52 UTCEG score recompute
  46. 2026-08-20 18:51 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-53583?
CVE-2026-53583 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, verifyservercert in src/libgit2/streams/openssl.c uses an inverted !!memcmp result in the GEN_IPADD…
When was CVE-2026-53583 disclosed?
CVE-2026-53583 was first published in the National Vulnerability Database on August 20, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-53583 actively exploited?
CVE-2026-53583 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 90.9% of all scored CVEs.
What is the CVSS score of CVE-2026-53583?
CVE-2026-53583 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2026-53583?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-53583, 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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