CVE-2026-53583

MEDIUMPre-NVD 6.56.5
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This medium-severity CVE scores 6.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2% (14th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Elevated

Also known asEUVD-2026-63549 (ENISA EUVD)Source: ENISA EUVD

6.5EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 6.5Exploit: No code on recordExposed services: Not assessed

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
6.5MEDIUMmedium confidence
EG Risk
60
EG Risk 60/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity65% × 45%
Impact severity (EG Severity): CVSS 6.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.2%
EPSS %ILE
14th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (6.5): severity, escalated by confirmed exploitation. This CVE's 6.5 is its impact severity (EG Severity), not escalated.

EG Severity
6.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-25). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 20, 2026

Last Modified

October 26, 2026

Advisory Details (6)

Auto-updated Aug 20, 2026
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 advisoryMentions a patch (unverified)

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(2)

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 / EcosystemFix (by version range) / PatchReleasedSource
ubuntulibgit2-fixtures (1.9.1+ds-1ubuntu1.3) @ resolute2026-10-26ubuntu
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 rangeFix by version rangeDependents
libgit21.5.1+ds-1 ... 1.9.7+ds-1 (32 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
libgit21.9.0+ds-2
  • every version up to 1.9.0+ds-2+deb13u1: fixed in 1.9.0+ds-2+deb13u1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
libgit21.9.0+ds-2 ... 1.9.4+ds-1 (13 versions)
  • every version up to 1.9.6+ds-1: fixed in 1.9.6+ds-1
—

Weakness Classification(2)

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 7× in last 7d / 50× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 98 of 154 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 2 repeat rows among the latest 100 are merged into the row they repeat. The 56 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  2. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  3. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  4. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  5. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  6. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  7. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  8. 2026-10-26 10:26 UTCEG score recompute
  9. 2026-10-26 10:26 UTCVendor advisory
  10. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  11. 2026-10-25 14:20 UTCEG score recompute
  12. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  13. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  14. 2026-10-22 21:48 UTCEG score recompute
  15. 2026-10-22 21:48 UTCVendor advisory
  16. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  17. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  18. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  19. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  20. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  21. 2026-10-18 03:31 UTCEG score recompute
  22. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  23. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  24. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  25. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.2% · 13th percentile
Show 73 more
  1. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  2. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  3. 2026-10-12 15:57 UTCEG score recompute
  4. 2026-10-11 19:40 UTCEG score recompute
  5. 2026-10-11 16:55 UTCEG score recompute
  6. 2026-10-11 14:19 UTCEG score recompute
  7. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  9. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  10. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  11. 2026-10-08 07:29 UTCEG score recompute
  12. 2026-10-08 07:29 UTCVendor advisory
  13. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  14. 2026-10-07 05:24 UTCEG score recompute
  15. 2026-10-07 05:24 UTCVendor advisory
  16. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  17. 2026-10-06 03:20 UTCVendor advisory
  18. 2026-10-06 03:20 UTCEG score recompute
  19. 2026-10-06 03:20 UTCVendor advisory
  20. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  21. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  22. 2026-10-04 20:51 UTCVendor advisory
  23. 2026-10-03 16:54 UTCEG score recompute
  24. 2026-10-03 16:54 UTCVendor advisory
  25. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  26. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  27. 2026-10-02 14:50 UTCEG score recompute
  28. 2026-10-02 14:50 UTCVendor advisory
  29. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  30. 2026-10-01 12:03 UTCEG score recompute
  31. 2026-10-01 12:03 UTCVendor advisory
  32. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  33. 2026-09-30 09:37 UTCEG score recompute
  34. 2026-09-30 09:37 UTCVendor advisory
  35. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  36. 2026-09-29 07:18 UTCEG score recompute
  37. 2026-09-29 07:18 UTCVendor advisory
  38. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  39. 2026-09-28 05:01 UTCEG score recompute
  40. 2026-09-28 05:01 UTCVendor advisory
  41. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  42. 2026-09-27 02:57 UTCEG score recompute
  43. 2026-09-27 02:57 UTCVendor advisory
  44. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  45. 2026-09-25 03:50 UTCEG score recompute
  46. 2026-09-25 03:50 UTCVendor advisory
  47. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  48. 2026-09-24 01:46 UTCEG score recompute
  49. 2026-09-24 01:46 UTCVendor advisory
  50. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  51. 2026-09-22 23:43 UTCEG score recompute
  52. 2026-09-22 23:43 UTCVendor advisory
  53. 2026-09-21 21:31 UTCEG score recompute
  54. 2026-09-21 21:31 UTCVendor advisory
  55. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  56. 2026-09-20 19:22 UTCVendor advisory
  57. 2026-09-19 17:18 UTCEG score recompute
  58. 2026-09-19 17:18 UTCVendor advisory
  59. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  60. 2026-09-18 15:14 UTCEG score recompute
  61. 2026-09-18 15:14 UTCVendor advisory
  62. 2026-09-17 13:10 UTCEG score recompute
  63. 2026-09-17 13:10 UTCVendor advisory
  64. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  65. 2026-09-16 10:46 UTCEG score recompute
  66. 2026-09-16 10:46 UTCVendor advisory
  67. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  68. 2026-09-15 08:33 UTCEG score recompute
  69. 2026-09-15 08:33 UTCVendor advisory
  70. 2026-09-14 06:29 UTCEG score recompute
  71. 2026-09-14 06:29 UTCVendor advisory
  72. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  73. 2026-09-13 04:26 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-53583?
CVE-2026-53583 is a medium-severity vulnerability; its CVE record was 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, verify_server_cert in src/libgit2/streams/openssl.c uses an inverted !!memcmp result in the GEN_IPADD…
When was the CVE record for CVE-2026-53583 published?
The CVE record for CVE-2026-53583 was published on August 20, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 26, 2026; the record at its source may have been updated since.
Is CVE-2026-53583 actively exploited?
CVE-2026-53583 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (14th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-53583?
CVE-2026-53583 has a CVSS base score of 6.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-53583?
A fix for CVE-2026-53583 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-53583 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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