# CVE-2026-54284: sqlparse TokenList CPU denial of service

Source: https://junglewise.ai/threats/cve-2026-54284-sqlparse-tokenlist-cpu-denial-of-service  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-17. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-54284 · Severity: high · CVSS 4 · Published 2026-08-17

sqlparse is a Python SQL parsing library used in web-based SQL formatters, Django debug toolbars, and metadata extraction tools. The parser's grouping logic performs wasteful subtree traversals during construction of nested SQL structures, allowing an attacker to submit a small malicious SQL query (1-2 KB) that consumes 10+ seconds of CPU on a single server worker. This enables denial-of-service attacks: one request locks a worker, and multiple concurrent requests exhaust a multi-worker deployment.

Technologies: [sqlparse (PyPI)](https://junglewise.ai/threats/technologies/sqlparse). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-54284 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-54284 being exploited in the wild.

**How severe is CVE-2026-54284?** High severity, with a CVSS score of 4, published 17 August 2026.

**Which products and versions are affected?** sqlparse (PyPI) <= 0.5.5, ECOSYSTEM:introduced=0,fixed=0.6.0.

**Is there a fix for CVE-2026-54284?** Yes. sqlparse (PyPI): upgrade to 0.6.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-54284 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-54284?** Check whether you run sqlparse (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- sqlparse (PyPI): upgrade to 0.6.0 or later

  ```sh
  pip install "sqlparse>=0.6.0"
  ```


## Technical details

The vulnerability exists in sqlparse/sql.py TokenList.__init__, which calls super().__init__(None, str(self)) to materialize the cached value field. TokenList.__str__ recursively flattens the entire token subtree via the flatten() method. During nested SQL grouping (parentheses, CASE WHEN, subqueries, ARRAY literals), a new TokenList is constructed for each group, and each construction triggers a full subtree walk. For a parse tree of depth d with n total tokens, this results in O(n*d) flatten work, causing quadratic complexity independent of the existing MAX_GROUPING_DEPTH=100 and MAX_GROUPING_TOKENS=10000 caps. Entry points sqlparse.parse(), sqlparse.format(reindent=True), and sqlparse.split() are vulnerable by default. The exploit requires only sending the malicious SQL to an application that processes user input; no authentication or special configuration is needed. Fix is available in version 0.6.0, replacing the eager str(self) materialization with a linear-time concatenation of already-cached child values.

## Affected products

- sqlparse sqlparse <= 0.5.5

## Identifiers

- CVE-2026-54284
- GHSA-pwgv-4x5q-6m9f
- PYSEC-2026-3699

## Timeline

- 2026-08-13: disclosed
- 2026-08-17: advisory
- 2026-08-17: patched: Fixed in version 0.6.0

## References

- [https://api.github.com/users/tonghuaroot](https://api.github.com/users/tonghuaroot)
- [https://github.com/tonghuaroot](https://github.com/tonghuaroot)
- [https://api.github.com/users/tonghuaroot/gists%7B/gist_id%7D](https://api.github.com/users/tonghuaroot/gists%7B/gist_id%7D)
- [https://api.github.com/users/tonghuaroot/repos](https://api.github.com/users/tonghuaroot/repos)
- [https://avatars.githubusercontent.com/u/23011166?v=4](https://avatars.githubusercontent.com/u/23011166?v=4)
- [https://api.github.com/users/tonghuaroot/events%7B/privacy%7D](https://api.github.com/users/tonghuaroot/events%7B/privacy%7D)

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- [PYSEC-2026-1940 - sqlparse parsing heavily nested list leads to Denial of Service](https://junglewise.ai/threats/cve-2024-4340-sqlparse-denial-of-service-via-heavily-nested-list)