Medium severity · published Jul 31, 2026
CVE-2026-64607
Apache HttpComponents Client: Connection Leak on Content-Encoding Decode Error Leads to Pool Exhaustion DoS
5.3
CVSS
0.5%
EPSS
No
On KEV
Description
HttpClient based on the classic i/o model fails to correctly release the underlying connection back to the connection manager if it encounters an invalid or unsupported `Content-Encoding` header value in the response message. Please note this defect does not affect HttpClient based on the async i/o model.
This issue affects Apache HttpComponents Client: from 5.0-alpha1 through 5.6.2.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 40% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
AH
Apache HttpComponents Client · Apache Software Foundation
5.0-alpha through 5.6.2 · source: vendor
HT
Httpclient · Apache
5.0.0 before 5.6.3 · source: NVD
Affected product
AH
Apache HttpComponents Client
Apache Software Foundation
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-64607
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-64607
Mailing List
https://lists.apache.org/thread/qqfzo3fqcdk4l5496vz95ppvl4ty511q
www.openwall.com
http://www.openwall.com/lists/oss-security/2026/08/13/5
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