PatchTheCVECVE-2026-64607: HttpClient based on the classic i/o model fails to correctly release the underlying connection back to the con
38
Routine
MEDIUM 5.3REMOTEWATCHLISTUPGRADE
CVE-2026-64607 is a medium-severity flaw (CVSS 5.3) affecting httpclient. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Why this priority
- Remotely exploitable, no login, no user action
- On your watchlist
A fixed release or distro patch exists.
Risk facts
| CVSS score | 5.3 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.5% (top 61%) |
| CISA exploited list | No |
| Weakness | CWE-772 |
| Published | 2026-07-31 |
| Last modified | 2026-10-23 |
Publisher (CNA): Apache Software Foundation · Vendor: apache
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
apache httpclient UPGRADE
Affected: >= 5.0.0 and < 5.6.3
Fixed in: 5.6.3
Safe to downgrade to: a release before 5.0.0
1. Check installed version
apt-cache policy httpclient || rpm -q httpclient || httpclient --version
2. UPGRADE to 5.6.3 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade httpclient
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade httpclient
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 5.0.0 (Debian / Ubuntu)
apt-cache madison httpclient
sudo apt install httpclient=<VERSION_BEFORE_5.0.0>
sudo apt-mark hold httpclient
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list httpclient
sudo dnf downgrade httpclient-<VERSION_BEFORE_5.0.0>
sudo dnf versionlock add httpclient
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Related CVEs
- CVE-2026-71290 CRITICAL 9.1 UPGRADE Improper TLS hostname verification vulnerability in Apache HttpComponents Client 5.4 or newer. HostnameVerific