CVE-2026-84305: sqlparse: Reindentation of tuple lists causes near-cap quadratic CPU consumption

Severity: medium (CVSS 5.1 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-01 · updated 2026-09-09
Weakness: CWE-407

Description

sqlparse is a non-validating SQL parser module for Python. Prior to 0.6.0, sqlparse.format(sql, reindent=True) and sqlformat --reindent route attacker-controlled parenthesized tuple lists through ReindentFilter._get_offset() in sqlparse/filters/reindent.py, where _flatten_up_to_token() repeatedly rebuilds and joins the statement prefix. Thousands of offset calculations walk an expanding token tree, producing quadratic CPU consumption for inputs that remain below MAX_GROUPING_TOKENS and causing request delays, reduced throughput, or worker starvation. This issue is fixed in version 0.6.0.

Affected products

Pypi Sqlparse: before 0.6.0; 0.1.0, 0.1.1, 0.1.10, 0.1.11, 0.1.12, 0.1.13 (+32) — fixed in 0.6.0
andialbrecht sqlparse: before 0.6.0

How to fix

Upgrade to a fixed version: Pypi Sqlparse 0.6.0. Check the vendor advisory for mitigations.

References

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