CPU exhaustion via comment-tail rescanning
Published Aug 17, 2026 · Updated Aug 17, 2026
Denial of service in sqlparse before 0.6.0 allows attackers to cause excessive CPU consumption via comment-only SQL statements. The group_comments function in sqlparse/engine/grouping.py rescans the remaining comment and newline token tail for each comment before the MAX_GROUPING_TOKENS guard, so sqlparse.parse() and sqlparse.format(sql, strip_comments=True) perform quadratic work on comment-only input. Exposure requires an attacker-controlled SQL string to reach code that parses or strips comments with sqlparse; the result is a hang or severe slowdown rather than code execution or data access.
Summary
What happened
Denial of service in sqlparse before 0.6.0 allows attackers to cause excessive CPU consumption via comment-only SQL statements. The group_comments function in sqlparse/engine/grouping.py rescans the remaining comment and newline token tail for each comment before the MAX_GROUPING_TOKENS guard, so sqlparse.parse() and sqlparse.format(sql, strip_comments=True) perform quadratic work on comment-only input. Exposure requires an attacker-controlled SQL string to reach code that parses or strips comments with sqlparse; the result is a hang or severe slowdown rather than code execution or data access.
The record
- CVE
- CVE-2026-71491
- Published
- Aug 17, 2026
- Updated
- Aug 17, 2026
- Vendor
- Andi Albrecht
- Product
- sqlparse
- Classifications
- CWE-400, CWE-407, T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 17, 2026CVE publishedPublication date reported by the CVE source.
- Aug 17, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 0.6.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- GitHub advisory PoC for comment-only statement DoSproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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