CVE-2026-64607

Q: How do I fix CVE-2026-64607?

Upgrade httpclient to 5.6.3 or later.

Q: Is CVE-2026-64607 being actively exploited?

Not that we know of. CVE-2026-64607 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.48% is the estimated probability that it will be exploited in the next 30 days. That is higher than 39% of all scored CVEs.

Q: How severe is CVE-2026-64607?

CVE-2026-64607 has a CVSS v3 base score of 5.3, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

Q: What does CVE-2026-64607 affect?

Published advisories record a fix for httpclient (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

MEDIUM

5.3

CVSS v3

NVD

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.

CWE-772

How to fix

Remediation Available

httpclientNVD

Affected:>= 5.0.0, < 5.6.3Fixed in:5.6.3CVE-2026-64607derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityLow

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Exploit Intelligence

0.48%probability of exploitation in 30 days

39thpercentile

Low risk: more likely to be exploited than 39% of all known CVEs.

References

Mailing List1

lists.apache.org

Other references1

openwall.com

Related Vulnerabilities

Other CWE-772 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2003-0132	Medium	5.0	87%	-	Fix
CVE-2017-14495	High	7.5	84%	-	Fix
CVE-2021-22883	High	7.5	74%	-	Fix
CVE-2024-2398	High	8.6	36%	-	Fix
CVE-2020-9375	High	7.5	27%	-	-
CVE-1999-1127	High	7.5	18%	-	-

Common questions

How do I fix CVE-2026-64607?

Upgrade httpclient to 5.6.3 or later.

Is CVE-2026-64607 being actively exploited?

Not that we know of. CVE-2026-64607 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.48% is the estimated probability that it will be exploited in the next 30 days. That is higher than 39% of all scored CVEs.

How severe is CVE-2026-64607?

CVE-2026-64607 has a CVSS v3 base score of 5.3, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-64607 affect?

Published advisories record a fix for httpclient (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-13.