CVE-2026-53583: libgit2 · Improper Certificate Validation
Affects libgit2Source GCVE Database
Not known to be exploited · CVSS 6.5 Medium : upgrade to 1.9.5 or 1.8.6 when convenient.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 14% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 1.9.5, 1.8.6
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 20 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade libgit2 to 1.9.5 or 1.8.6.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| libgit2 libgit2 | Affected
| Fixed in
|
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, 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.
References
- github.com/libgit2/libgit2/security/advisories/GHSA-h7gc-w2gg-p9xp (opens in a new tab)
- github.com/libgit2/libgit2/commit/647dcb432980b84ede4cb5a008bbd1ccb4ead03d (opens in a new tab)
- github.com/libgit2/libgit2/commit/c2aa35409ee0e6515df64da49750f13a0a42c47f (opens in a new tab)
- github.com/libgit2/libgit2/commit/ef086bc3e4eedf62be38a910381aae24d49871ff (opens in a new tab)
- github.com/libgit2/libgit2/releases/tag/v1.8.6 (opens in a new tab)
- github.com/libgit2/libgit2/releases/tag/v1.9.5 (opens in a new tab)