CVE-2024-21503: black
Vulnerability summary
CVE-2024-21503 is a medium (CVSS 5.3) vulnerability in black. EPSS estimates a 0.98% chance of exploitation in the next 30 days, higher than 62.2% of scored vulnerabilities.
Not severe (CVSS 5.3, network access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 1 · Related 2Timeline
- 19-03-2024PublishedVulnerability first disclosed.
- 01-08-2024Last modifiedVulnerability information updated.
Description
Versions of the package black before 24.3.0 are vulnerable to Regular Expression Denial of Service (ReDoS) via the lines_with_leading_tabs_expanded function in the strings.py file. An attacker could exploit this vulnerability by crafting a malicious input that causes a denial of service. Exploiting this vulnerability is possible when running Black on untrusted input, or if you habitually put thousands of leading tab characters in your docstrings.
CVSS metrics
7 scores · 7 sources · 1 version- OSV · PypiEcosystem advisory · calculated5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- OSV · UbuntuEcosystem advisory · calculated5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- OSV · DebianEcosystem advisory · calculated5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- NVDNIST5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- OSV · ChainguardEcosystem advisory · calculated5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:P
- OSV · AlpineEcosystem advisory · calculated5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS trend
Probability
0.98%
Chance of exploitation in the next 30 days
Percentile
62%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.98% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-1333Inefficient Regular Expression ComplexityThe product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.
- CWE-75Failure to Sanitize Special Elements into a Different PlaneThe product does not adequately filter user-controlled input for special elements with control implications.
Affected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Opensuse2 products
- python-black&distro=openSUSE Leap 15.6< 24.3.0-150400.9.8.1
- python-black&distro=openSUSE Tumbleweed< 26.5.1-1.3
Alpine1 product
- black< 23.12.0-r0 | < 24.3.0-r0
Chainguard1 product
- nemo< 1.23.0-r12
Debian1 product
- blackAll versions (No fix recorded) | < 24.4.0-1
PyPI1 product
- black< f00093672628d212b8965a8993cee8bedf5fe9b8 | < 24.3.0
Ubuntu1 product
- blackAll versions (No fix recorded)
6 vendors · 7 products
References
15 links
- github.com/psf/blackPACKAGE
