CVE-2021-32839: Regular Expression Denial of Service in sqlparse

Severity: medium (CVSS 5.0 v2.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-09-20 · updated 2026-06-17
Weakness: CWE-400

Description

sqlparse is a non-validating SQL parser module for Python. In sqlparse versions 0.4.0 and 0.4.1 there is a regular Expression Denial of Service in sqlparse vulnerability. The regular expression may cause exponential backtracking on strings containing many repetitions of '\r\n' in SQL comments. Only the formatting feature that removes comments from SQL statements is affected by this regular expression. As a workaround don't use the sqlformat.format function with keyword strip_comments=True or the --strip-comments command line flag when using the sqlformat command line tool. The issues has been fixed in sqlparse 0.4.2.

Affected products

andialbrecht sqlparse: from 0.4.0 before 0.4.2 — fixed in 0.4.2
Pypi Sqlparse: from 0.4.0 before 0.4.2; 0.4.0, 0.4.1 — fixed in 0.4.2

How to fix

Upgrade to a fixed version: andialbrecht sqlparse 0.4.2; Pypi Sqlparse 0.4.2. Check the vendor advisory for mitigations.

References

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