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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之前版本存在安全漏洞，该漏洞源于src/libgit2/transports/smart_pkt.c的set_data函数中未验证缓冲区长度即执行固定大小strncmp，导致堆越界访问，可能使客户端在首次refs-advertisement包时崩溃。

CVSS 7.5 · High EPSS 0.47% · P39

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
Vulnerability Title
libgit2 缓冲区错误漏洞
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之前版本存在安全漏洞，该漏洞源于src/libgit2/transports/smart_pkt.c的set_data函数中未验证缓冲区长度即执行固定大小strncmp，导致堆越界访问，可能使客户端在首次refs-advertisement包时崩溃。
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-2026-53587

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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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