Medium 6.5Published Aug 20, 2026

CVE-2026-53583libgit2: Inverted IP SubjectAltName Comparison in OpenSSL Backend

Updated under an hour ago (2026-10-19 10:10 UTC)

Does this affect you?

It affects libgit2. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

Do this next

Start free and add your stack

Free account, 1 product

Every CVE for libgit2

Exploited in the last 30 days

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: 6.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Weakness (CWE): CWE-295, CWE-297
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Awaiting Analysis
Record last updated: Aug 20, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

libgit2 libgit2 libgit2:libgit2 (from the name)	before 1.8.6; from 1.9.0, < 1.9.5	CNA record

References

https://github.com/libgit2/libgit2/security/advisories/GHSA-h7gc-w2gg-p9xpx-refsource-confirm
https://github.com/libgit2/libgit2/commit/647dcb432980b84ede4cb5a008bbd1ccb4ead03dx-refsource-misc
https://github.com/libgit2/libgit2/commit/c2aa35409ee0e6515df64da49750f13a0a42c47fx-refsource-misc
https://github.com/libgit2/libgit2/commit/ef086bc3e4eedf62be38a910381aae24d49871ffx-refsource-misc
https://github.com/libgit2/libgit2/releases/tag/v1.8.6x-refsource-misc
https://github.com/libgit2/libgit2/releases/tag/v1.9.5x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.