# CVE-2026-64607: Apache HttpComponents Client: Connection Leak on Content-Encoding Decode Error Leads to Pool Exhaustion DoS > Attackers can cause connection pool exhaustion and denial of service by sending responses with invalid Content-Encoding headers to applications using the classic I/O model. - **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 31 Jul 2026 - **Updated:** 13 Aug 2026 - **Also known as:** CLEANSTART-2026-EK15836, CLEANSTART-2026-FO83563, CLEANSTART-2026-HB58573, CLEANSTART-2026-LH05062, CLEANSTART-2026-RC74250, CLEANSTART-2026-SO94492, CLEANSTART-2026-XL17660, CLSA-2026-1786537061, CLSA-2026-1789373020, CLSA-2026-1789474443, CLSA-2026-1792743499, CLSA-2026-1792743815, CLSA-2026-1792744283, DEBIAN-CVE-2026-64607, ECHO-315f-89e1-2302, GHSA-hjcp-jmpx-g3qm, MINI-26mh-mpvg-jvfj, MINI-2q5v-584p-6vj4, MINI-3p2c-82xr-jh42, MINI-43qp-gxv5-6xf8, MINI-4cfq-4qw9-hxgv, MINI-5324-q6pw-vfjm, MINI-573j-q8w8-wff5, MINI-5x3c-rvrf-6ppg, MINI-6xx7-f2mg-g7vr, MINI-9j4r-9x6r-x2gp, MINI-c3v8-6vvp-m4v6, MINI-crfv-8cj8-cg6r, MINI-cvhh-fcxc-72g5, MINI-f538-p42q-qpqx, MINI-fh7r-vx99-5r5g, MINI-fwph-pgqg-87xm, MINI-g988-4cq6-qhv7, MINI-h7rp-cprf-f9vq, MINI-hgm2-rgp9-mxx4, MINI-j5rm-ppf4-wwcw, MINI-jfc7-39pr-rmr9, MINI-m24q-v972-x73q, MINI-m7q7-wmrp-9gcf, MINI-pg85-wgwv-j59g, MINI-pgc2-4q6q-r3qh, MINI-pmqr-v96g-w55c, MINI-qhp3-qwxg-xrff, MINI-vg9f-7wv3-hhm8, MINI-vgx7-g3j6-23p6, MINI-vpxj-hc65-8mfw, MINI-wm66-r32w-gqg2, MINI-x2h3-2w74-jg45, MINI-xwmp-88gr-fqj6, MINI-xx69-jrqr-q8v7, RHLW-2026-8118b2499151de91, SUSE-SU-2026:4028-1, UBUNTU-CVE-2026-64607, openSUSE-SU-2026:11647-1, openSUSE-SU-2026:21894-1 ## What is CVE-2026-64607? CVE-2026-64607 is a medium-severity denial of service vulnerability in Apache HttpComponents Client, published on 31 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official 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. Weakness: CWE-772 (Missing Release of Resource after Effective Lifetime) ## Which versions are affected by CVE-2026-64607? 2 open source packages ship an affected version, including org.apache.httpcomponents.client5:httpclient5. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `org.apache.httpcomponents.client5:httpclient5` | Maven | From 5.0-alpha1 | 5.6.3 | | `org.apache.httpcomponents.client5:httpclient5` | Maven | From 5.0-alpha1 | 5.6.3 | | `httpcomponents-client` | SUSE:Linux Enterprise Module for Development Tools 15 SP7 | All versions | 4.5.14-150200.3.12.1 | | `httpcomponents-client` | openSUSE:Leap 16.0 | All versions | 4.5.14-160000.4.1 | | `httpcomponents-client` | openSUSE:Tumbleweed | All versions | 4.5.14-2.1 | Products: Apache Httpclient. ## How do I fix CVE-2026-64607? Upgrade org.apache.httpcomponents.client5:httpclient5 to 5.6.3 or later. ## Is CVE-2026-64607 being exploited? There is no known exploitation of CVE-2026-64607 in the wild and no public exploit code. ## Other vulnerabilities in Apache HttpComponents Client - [CVE-2013-4366](https://insights.sbomify.com/CVE-2013-4366/): Hostname verification in Apache HttpClient 4.3 was disabled by default (critical 9.8) - [CVE-2026-71290](https://insights.sbomify.com/CVE-2026-71290/): Apache HttpComponents Client: TLS hostname verification silently disabled on the async transport (default config, MITM) (critical 9.1) - [CVE-2025-27820](https://insights.sbomify.com/CVE-2025-27820/): Apache HttpComponents: PSL (Public Suffix List) validation bypass (high 7.5) - [CVE-2026-40542](https://insights.sbomify.com/CVE-2026-40542/): Apache HttpClient accepts SCRAM-SHA-256 authentication without proper mutual authentication verification (high 7.3) - [CVE-2012-5783](https://insights.sbomify.com/CVE-2012-5783/): Improper Certificate Validation in Apache Commons HttpClient (medium 5.8) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-64607 and fix it if it is affected. What it is: CVE-2026-64607 is a medium-severity denial of service vulnerability in Apache HttpComponents Client, published on 31 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-64607 in the wild and no public exploit code. Affected packages and fixed versions: - org.apache.httpcomponents.client5:httpclient5 (Maven): affected from 5.0-alpha1; fixed in 5.6.3 - org.apache.httpcomponents.client5:httpclient5 (Maven): affected from 5.0-alpha1; fixed in 5.6.3 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-64607/ (Markdown: https://insights.sbomify.com/CVE-2026-64607/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64607 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64607 - OSV: https://osv.dev/vulnerability/CVE-2026-64607 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-64607/ Summaries are generated and may contain mistakes; the official description above is the record.