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CVE-2026-53585— libgit2: Unbounded Memory Allocation via Delta Object Result-Size Header

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，提供了 Git 核心方法的链接库形式，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 1.8.6 和 1.9.5 版本之前，位于 中的 函数存在安全问题：它信任由 delta 对象头解析出的、由攻击者控制的 值（该值源自 ），并在验证 delta 指令之前，将该大小直接传递给 进行内存分配。攻击者可以通过 、 、 、 或本地攻击者提供的仓库等途径，注入恶意的 pack 数据，利用极小层级的多级别 OFS_DELTA 链结构，保留并触发极大的内

CVSS 5.3 · Medium EPSS 0.55% · P44

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-2026-53585

Vulnerability Information
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Vulnerability Title
libgit2: Unbounded Memory Allocation via Delta Object Result-Size Header
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, git_delta_apply in src/libgit2/delta.c trusts the attacker-controlled res_sz value parsed by hdr_sz from a delta object header and passes that amount to git__malloc before validating delta instructions. Malicious pack data supplied through git_clone, git_fetch, git_remote_fetch, git_indexer_append, or a local attacker-supplied repository can use a very small multi-level OFS_DELTA chain to retain extremely large allocations and exhaust memory. 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:L
Source: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
libgit2 libgit2 < 1.8.6 -

II. Public POCs for CVE-2026-53585

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III. Intelligence Information for CVE-2026-53585

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Patches & Fixes for CVE-2026-53585 (4)

Vendor Advisories for CVE-2026-53585 (1)

Vendor Pages for CVE-2026-53585 (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-2026-53583 6.5 MEDIUM libgit2: Inverted IP SubjectAltName Comparison in OpenSSL Backend
CVE-2026-53584 4.3 MEDIUM libgit2: Submodule path traversal

IV. Related Vulnerabilities

Same product: libgit2
Same vendor: libgit2
Same weakness: CWE-770

V. Comments for CVE-2026-53585

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