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

Quick assessment

Affected
libgit2 libgit2
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

libgit2是Libgit2团队开源的一款可嵌入的Git版本控制库。 libgit2 1.8.6之前版本和1.9.0至1.9.5之前版本存在加密问题漏洞，该漏洞源于OpenSSL构建中验证IP证书时反转了memcmp结果，可能允许网络攻击者利用包含任意IP SubjectAltName的CA信任证书拦截libgit2到IP字面量HTTPS URL的连接。

CVSS 6.5 · Medium EPSS 0.24% · P14

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 2

VendorProduct Version RangeStatus
libgit2 libgit2 < 1.8.6 affected
>= 1.9.0, < 1.9.5 affected
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I. Basic Information for CVE-2026-53583

Vulnerability Information
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Vulnerability Title
libgit2: Inverted IP SubjectAltName Comparison in OpenSSL Backend
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
证书验证不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
libgit2 加密问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
libgit2是Libgit2团队开源的一款可嵌入的Git版本控制库。 libgit2 1.8.6之前版本和1.9.0至1.9.5之前版本存在加密问题漏洞，该漏洞源于OpenSSL构建中验证IP证书时反转了memcmp结果，可能允许网络攻击者利用包含任意IP SubjectAltName的CA信任证书拦截libgit2到IP字面量HTTPS URL的连接。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
libgit2 libgit2 < 1.8.6 -

II. Public POCs for CVE-2026-53583

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III. Intelligence Information for CVE-2026-53583

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Patches & Fixes for CVE-2026-53583 (4)

Vendor Advisories for CVE-2026-53583 (1)

Vendor Pages for CVE-2026-53583 (1)

Same Patch Batch · libgit2 · 2026-08-20 · 5 CVEs total

CVE-2026-53587 7.5 HIGH libgit2 - Unauthenticated network-reachable heap out-of-bounds read in transports/smart_pk
CVE-2026-53586 6.5 MEDIUM libgit2: HTTP transport can leak credentials to an offsite redirect target
CVE-2026-53585 5.3 MEDIUM libgit2: Unbounded Memory Allocation via Delta Object Result-Size Header
CVE-2026-53584 4.3 MEDIUM libgit2: Submodule path traversal

IV. Related Vulnerabilities

Same product: libgit2
Same vendor: libgit2
Same weakness: CWE-295

V. Comments for CVE-2026-53583

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