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CVE-2026-41140 high CVSS 8.7

Path Traversal in poetry (CVE-2026-41140)

Summary

Path traversal in poetry (CVE-2026-41140). Data can be tampered with by attackers. Exploitable via tarfile.data_filter. Mitigation: upgrade to 2.3.4 or later.

Original description

The description as published by the source.

Summary

The extractall() function in src/poetry/utils/helpers.py:410-426 extracts sdist tarballs without path traversal protection on Python versions where tarfile.data_filter is unavailable. Considering only Python versions which are still supported by Poetry, these are 3.10.0 - 3.10.12 and 3.11.0 - 3.11.4.

Impact

Arbitrary file write (path traversal) from untrusted sdist content.

In practice, the impact is low because an attacker who exploits this vulnerability can as well include arbitrary code in a setup.py, which will be executed when the sdist is built after tar extraction. In other words, a malicious sdist can write arbitrary files by design. However, since it is unexpected and not by design that the file write already happens during tar extraction, this is still considered a vulnerability.

On Python 3.11.2 (Debian Bookworm default, directly tested), a crafted sdist with ../../ tar member paths writes files outside the intended extraction directory. The traversal occurs during metadata resolution (poetry add --lock), before the build backend is run.

Affected Environments:

  • Python 3.10.0 through 3.10.12 (inclusive): tarfile.data_filter absent or broken
  • Python 3.11.0 through 3.11.4 (inclusive): tarfile.data_filter absent or broken
  • Debian Bookworm: Python 3.11.2 (default)
  • Ubuntu 22.04 LTS: Python 3.10.6 (default)

Patches

Versions 2.3.4 and newer of Poetry ensure that paths are inside the target directory.

##…

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-41140 has been found in poetry.
Attackers can target a specific entry point like tarfile.data_filter over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 8.7/10.
What to do: upgrade poetry to 2.3.4 or later.
If unsure, ask your IT team or search "poetry CVE-2026-41140" on the vendor's site.

CVE-2026-41140 (poetry) — CWE-22 / CVSS v3 8.7
Attack vector: remote (network-reachable)
Attack surface: tarfile.data_filter / setup.py / else / _prepare_sdist
Patched: 2.3.4 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

Path traversal (CWE-22) exists in poetry. Attackers reach the vulnerable code path via tarfile.data_filter.

📍 Affected scope

Check the vendor advisory for the affected versions of poetry. Attack surface: tarfile.data_filter / setup.py / else / _prepare_sdist.

🔥 Severity

Severity: High (CVSS 8.7/10). Data can be tampered with by attackers.

🔧 How to fix

Update to 2.3.4.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'poetry' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'poetry' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で poetry を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade poetry to 2.3.4

    ステージング環境で 2.3.4 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

PyPI poetry
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.3.4"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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