Bug 2521745

Summary: CVE-2026-53583 rust-libgit2-sys0.17: libgit2: Network attacker can intercept HTTPS connections via inverted IP SubjectAltName comparison [epel-all]
Product: [Fedora] Fedora EPEL Reporter: Vladimir Vasilev <vvasilev>
Component: rust-libgit2-sys0.17Assignee: Rust SIG <rust-sig>
Status: ASSIGNED --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: epel10CC: decathorpe, rust-sig
Target Milestone: ---Keywords: Security, SecurityTracking
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Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["8cf6c6b0-124c-4406-b0cc-b65f399b7adf"]}
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On:    
Bug Blocks: 2520694    

Description Vladimir Vasilev 2026-08-24 07:55:24 UTC 
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

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.
Comment 1 Fabio Valentini 2026-08-27 13:00:06 UTC 
As far as I can tell, the only application that still (transitively) depends on rust-libgit2-sys0.17 is rust-git-absorb, and only on the f43 and epel9 branches. I have submitted pull requests to resolve this in both these branches.