Service interruption via fragmented line limit bypass
Published Jun 22, 2026 · Updated Jun 22, 2026
Denial of service in aiohttp before 3.14.1 allows remote attackers to exhaust memory via fragmented oversized HTTP lines. The C parser callbacks for request targets and response reason phrases compare each fragment, rather than the accumulated buffer, with max_line_size. The issue is reachable without authentication when the optimized C parser is used, including its default use in pre-built wheels, and can interrupt an exposed client or server process through memory exhaustion.
Summary
What happened
Denial of service in aiohttp before 3.14.1 allows remote attackers to exhaust memory via fragmented oversized HTTP lines. The C parser callbacks for request targets and response reason phrases compare each fragment, rather than the accumulated buffer, with max_line_size. The issue is reachable without authentication when the optimized C parser is used, including its default use in pre-built wheels, and can interrupt an exposed client or server process through memory exhaustion.
The record
- CVE
- CVE-2026-54277
- Published
- Jun 22, 2026
- Updated
- Jun 22, 2026
- Vendor
- aio-libs
- Product
- aiohttp
- Classifications
- CWE-770, T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 22, 2026CVE publishedPublication date reported by the CVE source.
- Jun 22, 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=< 3.14.1
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
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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