Service interruption via leaked classic-I/O connections
Published Jul 31, 2026 · Updated Jul 31, 2026
Resource exhaustion in Apache HttpClient 5.0-alpha1 through 5.6.2 allows remote attackers to exhaust classic-I/O connection pools. ContentCompressionExec throws on an invalid or unsupported Content-Encoding value without closing the response, leaving its underlying connection allocated. Exploitation requires responses from an attacker-controlled server; repeated failures can interrupt requests made by the embedding application, while async-I/O clients are unaffected.
Summary
What happened
Resource exhaustion in Apache HttpClient 5.0-alpha1 through 5.6.2 allows remote attackers to exhaust classic-I/O connection pools. ContentCompressionExec throws on an invalid or unsupported Content-Encoding value without closing the response, leaving its underlying connection allocated. Exploitation requires responses from an attacker-controlled server; repeated failures can interrupt requests made by the embedding application, while async-I/O clients are unaffected.
The record
- CVE
- CVE-2026-64607
- Published
- Jul 31, 2026
- Updated
- Jul 31, 2026
- Vendor
- The Apache Software Foundation
- Product
- Apache HttpClient
- Classifications
- CWE-772, T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 31, 2026CVE publishedPublication date reported by the CVE source.
- Jul 31, 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=5.0-alpha <=5.6.2
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
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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