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CVE-2026-53587— libgit2 - Unauthenticated network-reachable heap out-of-bounds read in transports/smart_pkt.c:set_data

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 是一个可移植的 C 语言实现的 Git 核心方法库，以可链接库的形式提供，并具备稳定的 API，允许开发者将 Git 功能集成到自己的应用程序中。在版本 1.8.6 及 1.9.5 之前，libgit2 在 文件的 函数中执行固定长度的 操作时，未首先验证智能协议（smart-protocol）的 pkt-line 能力缓冲区是否包含至少 14 个字节。恶意 Git 服务器可以伪造在 中 之后的数据，导致 指针越过 pkt-line 的边界，并使后续 的长度计算发生下溢。这种堆缓冲区越界访问可能在客

CVSS 7.5 · High EPSS 0.39% · P32

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-2026-53587

Vulnerability Information
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Vulnerability Title
libgit2 - Unauthenticated network-reachable heap out-of-bounds read in transports/smart_pkt.c:set_data
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, libgit2 performs a fixed-size strncmp in set_data in src/libgit2/transports/smart_pkt.c without first verifying that the smart-protocol pkt-line capability buffer contains 14 bytes. A malicious Git server can make bytes after the pkt-line complete object-format=, causing format_str to advance beyond the pkt-line and the following memchr length calculation to underflow. The resulting heap out-of-bounds walk can crash a client during the first refs-advertisement packet over HTTP, HTTPS, SSH, or the Git protocol. 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:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
输入验证不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
libgit2 libgit2 < 1.8.6 -

II. Public POCs for CVE-2026-53587

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III. Intelligence Information for CVE-2026-53587

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Patches & Fixes for CVE-2026-53587 (4)

Vendor Advisories for CVE-2026-53587 (1)

Vendor Pages for CVE-2026-53587 (1)

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

CVE-2026-53586 6.5 MEDIUM libgit2: HTTP transport can leak credentials to an offsite redirect target
CVE-2026-53583 6.5 MEDIUM libgit2: Inverted IP SubjectAltName Comparison in OpenSSL Backend
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-20

V. Comments for CVE-2026-53587

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