PyPi: Black

CVE-2024-21503

Safety vulnerability ID: 66742

This vulnerability was reviewed by experts

The information on this page was manually curated by our Cybersecurity Intelligence Team.

Created at Mar 19, 2024 Updated at Dec 08, 2025
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Advisory

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Affected package

black

Latest version: 25.12.0

The uncompromising code formatter.

Affected versions

[This affected versions has been limited. Please create a free account to view the full affected versions.]

Fixed versions

[This fixed versions has been limited. Please create a free account to view the full fixed versions.]

Vulnerability changelog

Highlights

This release is a milestone: it fixes Black's first CVE security vulnerability. If you
run Black on untrusted input, or if you habitually put thousands of leading tab
characters in your docstrings, you are strongly encouraged to upgrade immediately to fix
[CVE-2024-21503](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-21503).

This release also fixes a bug in Black's AST safety check that allowed Black to make
incorrect changes to certain f-strings that are valid in Python 3.12 and higher.

Stable style

- Don't move comments along with delimiters, which could cause crashes (4248)
- Strengthen AST safety check to catch more unsafe changes to strings. Previous versions
of Black would incorrectly format the contents of certain unusual f-strings containing
nested strings with the same quote type. Now, Black will crash on such strings until
support for the new f-string syntax is implemented. (4270)
- Fix a bug where line-ranges exceeding the last code line would not work as expected
(4273)

Performance

- Fix catastrophic performance on docstrings that contain large numbers of leading tab
characters. This fixes
[CVE-2024-21503](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-21503).
(4278)

Documentation

- Note what happens when `--check` is used with `--quiet` (4236)

Resources

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Severity Details

CVSS Base Score

MEDIUM 5.3

CVSS v3 Details

MEDIUM 5.3
Attack Vector (AV)
NETWORK
Attack Complexity (AC)
LOW
Privileges Required (PR)
NONE
User Interaction (UI)
NONE
Scope (S)
UNCHANGED
Confidentiality Impact (C)
NONE
Integrity Impact (I)
NONE
Availability Availability (A)
LOW