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CVE-2026-85731— oras-go: Arbitrary file write outside file.Store root via symlink-chain bypass in tar extraction (pushDir)

Quick assessment

Affected
oras-project oras-go
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.

oras-go 是一个用于管理 OCI 制品的 Go 库。在 2.6.2 版本之前，当内容或文件存储（content/file.Store）提取标记为 的 OCI 层时，可能会在存储工作目录之外写入文件。 具体原因如下： 路径中的 和 函数仅以字面方式（lexical）验证符号链接的目标； 函数在处理根级条目时会跳过对父目录符号链接的遍历；而 函数在打开常规文件时会跟随终端符号链接。因此，一个恶意的归档文件可以构造一条符号链接链，其字面目标位于提取根目录内部，但实际解析后的目标却是攻击者选定的绝对路径。随后，即使

CVSS 8.8 · High
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I. Basic Information for CVE-2026-85731

Vulnerability Information
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Vulnerability Title
oras-go: Arbitrary file write outside file.Store root via symlink-chain bypass in tar extraction (pushDir)
Source: CVE Program / CVE List V5
Vulnerability Description
oras-go is a Go library for managing OCI artifacts. Prior to 2.6.2, content/file.Store extraction of OCI layers marked with io.deis.oras.content.unpack=true can write outside the store working directory. The pushDir path through extractTarDirectory and ensureLinkPath validates symlink targets lexically, resolveRelToBase skips its parent-symlink walk for root-level entries, and writeFile follows a terminal symlink when opening a regular file. A malicious archive can therefore create a symlink chain whose lexical target remains inside the extraction root but whose resolved target is an attacker-selected absolute path, then overwrite that target with a same-named regular-file entry even when AllowPathTraversalOnWrite is false. Pulling an attacker-controlled artifact can create or overwrite any file writable by the process and may lead to code execution. This issue is fixed in version 2.6.2.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
对路径名的限制不恰当(路径遍历)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
oras-project oras-go < 2.6.2 -

II. Public POCs for CVE-2026-85731

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III. Intelligence Information for CVE-2026-85731

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Patches & Fixes for CVE-2026-85731 (2)

Other References for CVE-2026-85731 (1)

IV. Related Vulnerabilities

Same product: oras-go
Same vendor: oras-project
Same weakness: CWE-22

V. Comments for CVE-2026-85731

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