How severe is CVE-2021-32839?

CVE-2021-32839 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-32839?

CVE-2021-32839 affects the following packages: sqlparse (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2021-32839?

Update sqlparse to 0.4.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-32839 is resolved across your whole dependency graph.

How do I detect CVE-2021-32839 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for sqlparse, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-32839 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2021-32839 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-32839 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-32839?

CVE-2021-32839 has an EPSS (Exploit Prediction Scoring System) score of 2.3%, placing it in the 83th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-32839?

CVE-2021-32839 is classified as Uncontrolled Resource Consumption (CWE-400). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-32839 published, and has it been updated?

CVE-2021-32839 was published on September 20, 2021 and was last updated on July 15, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

HIGH severity

CVE-2021-32839 — sqlparse

HIGHFix: andialbrecht/sqlparse@8238a9e

CVE-2021-32839 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in sqlparse. A fix is available for sqlparse — see the affected versions and patch details below.

StripComments filter contains a regular expression that is vulnerable to ReDOS (Regular Expression Denial of Service)

Also known asGHSA-p5w8-wqhj-9hhfPYSEC-2021-333

Published

Sep 20, 2021

Updated

Jul 15, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 1, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

2.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs83th percentile — riskier than 83% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-32839 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 381,682 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

🐍sqlparse

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Impact

The formatter function that strips comments from a SQL contains a regular expression that is vulnerable to ReDoS (Regular Expression Denial of Service). The regular expression may cause exponential backtracking on strings containing many repetitions of '\r\n' in SQL comments.

Patches

The issues has been fixed in sqlparse 0.4.2.

Workarounds

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.

References

This issue was discovered by GitHub team members @erik-krogh and @yoff. It was found using a CodeQL query which identifies inefficient regular expressions. You can see the results of the query on python-sqlparse by following this link.

For more information

If you have any questions or comments about this advisory:

Open an issue in sqlparse issue tracker
Email us at [email protected]

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`sqlparse`	≥ 0.4.0&&< 0.4.2	0.4.2`pip install --upgrade 'sqlparse==0.4.2'`

Affected Products

1 product · 1 configurations

Application

sqlparsesqlparse_project

≥ 0.4.0 && < 0.4.2

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for sqlparse, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update sqlparse to 0.4.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-32839 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Workaround published by Red Hat

As mitigation, 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.

Source: Red Hat security advisory for CVE-2021-32839 (CC BY 4.0)

Product	Fixed in	Advisory
Red Hat Satellite 6.11 for RHEL 8	`python-sqlparse-0:0.4.2-2.el8pc`	RHSA-2022:5498

UbuntuHIGH

USN-5085-1Ubuntu

Frequently Asked Questions

### Impact The formatter function that strips comments from a SQL contains a regular expression that is vulnerable to [ReDoS](https://owasp.org/www-community/attacks/Regular_expression_Denial_of_Service_-_ReDoS) (Regular Expression Denial of Service). The regular expression may cause exponential backtracking on strings containing many repetitions of '\r\n' in SQL comments. ### Patches The issues has been fixed in sqlparse 0.4.2. ### Workarounds Only the formatting feature that removes comments from SQL statements is affected by this regular expression. As a workaround don't use the `sqlforma