Bug 2535549 (CVE-2026-85731)

Summary: CVE-2026-85731 github.com/oras-project/oras-go: oras-go: Arbitrary file write and code execution via symlink-chain bypass
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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OS: Linux   
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A flaw was found in oras-go, a Go library for managing OCI (Open Container Initiative) artifacts. A remote attacker can exploit a symlink-chain bypass vulnerability during tar extraction of OCI layers. This allows a malicious archive to create or overwrite any file writable by the process outside the intended working directory. Successful exploitation may lead to arbitrary code execution.
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Bug Depends On: 2535577    
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Description OSIDB Bzimport 2026-09-16 16:43:21 UTC 
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.