How severe is CVE-2026-114134?

No CVSS score has been assigned to CVE-2026-114134 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-114134?

CVE-2026-114134 affects the following packages: black (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2026-114134?

Update black to 26.10.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-114134 is resolved across your whole dependency graph.

How do I detect CVE-2026-114134 in my PyPI dependencies?

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

How do I mitigate CVE-2026-114134 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2026-114134 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-114134 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.

When was CVE-2026-114134 published, and has it been updated?

CVE-2026-114134 was published on October 22, 2026 and was last updated on October 22, 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-2026-114134 — black

Fix: psf/black#5510

CVE-2026-114134 is a remote code execution vulnerability in black. A fix is available for black — see the affected versions and patch details below.

Black: GitHub Action installs unvalidated required-version from pyproject.toml

Published

Oct 22, 2026

Updated

Oct 22, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 22, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

🐍black

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

The GitHub Action bundled with Black can read the version from tool.black.required-version if use_pyproject is set to True. This version is not validated and therefore can be used to execute untrusted code in the context of a victim's repository.

Details

This is similar to the previous CVE-2026-31900. The value in tool.black.required-version is accepted as the version to be installed by the action without validation.

Proof of concept

Reproduction requires a victim to use Black's GitHub Action with use_pyproject: true. The attacker would then issue a PR to the victim's repository with pyproject.toml edited so that Black points to a malicious repository.

Impact

This is a remote code execution vulnerability impacting users using the GitHub Action bundled with psf/black and using the use_pyproject: true setting.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`black`	all versions	26.10.1`pip install --upgrade 'black==26.10.1'`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for black, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update black to 26.10.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-114134 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Summary The GitHub Action bundled with Black can read the version from `tool.black.required-version` if `use_pyproject` is set to True. This version is not validated and therefore can be used to execute untrusted code in the context of a victim's repository. ### Details This is similar to the previous CVE-2026-31900. The value in `tool.black.required-version` is accepted as the version to be installed by the action without validation. ### Proof of concept Reproduction requires a victim to use Black's GitHub Action with `use_pyproject: true`. The attacker would then issue a PR to the v

O3 Security · Impact-Aware SCA

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