Apache HttpComponents Client: Connection Leak on Content-Encoding Decode Error Leads to Pool Exhaustion DoS
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.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for help- Published
- Jul 31, 2026
- Updated
- Aug 13, 2026
- EPSS
- 0.5% · 38th percentile
- CWE
- CWE-772
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Report tools
Action score
21
Monitor
Low priority for now.
- CVSS
- 21 / 40 · 5.3 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.5%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| apache | httpclient | cpe:2.3:a:apache:httpclient |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- apache httpclient5.0.0 and later · before 5.6.3
Versions reported by the vendor
Affected version ranges reported by the assigning authority (apache). Independent of NVD's CPE analysis and usually ahead of it.
Apache Software Foundation Apache HttpComponents Client
- 5.0-alpha and later · up to and including 5.6.2affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | commons-httpclient | all versions | — |
| Debian:12 | httpcomponents-client | all versions | — |
| Maven | org.apache.httpcomponents.client5:httpclient5 | from 5.0-alpha1 · before 5.6.3 | 5.6.3 |
| openSUSE:Leap 16.0 | httpcomponents-client | before 4.5.14-160000.4.1 | 4.5.14-160000.4.1 |
| openSUSE:Tumbleweed | httpcomponents-client | before 4.5.14-2.1 | 4.5.14-2.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP7 | httpcomponents-client | before 4.5.14-150200.3.12.1 | 4.5.14-150200.3.12.1 |
Same product
apache: all recordsOther highest-scoring records for the same primary product.
- CVE-2013-4366http/impl/client/HttpClientBuilder.java in Apache HttpClient 4.3.x before 4.3.1 does not ensure that X509HostnameVerifier is not null, which40Plan
- CVE-2026-71290Apache HttpComponents Client: TLS hostname verification silently disabled on the async transport (default config, MITM)36Monitor
- CVE-2025-27820Apache HttpComponents: PSL (Public Suffix List) validation bypass30Monitor
- CVE-2026-40542Apache HttpClient: SCRAM-SHA-256 mutual authentication bypass may cause the client to accept authentication without proper mutual authentication verification29Monitor
- CVE-2014-3577org.apache.http.conn.ssl.AbstractVerifier in Apache HttpComponents HttpClient before 4.3.5 and HttpAsyncClient before 4.0.2 does not properl26Monitor
- CVE-2012-5783Apache Commons HttpClient 3.x, as used in Amazon Flexible Payments Service (FPS) merchant Java SDK and other products, does not verify that 26Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Maven:org.apache.httpcomponents.client5:httpclient5 | 5.6.3 | Package registry (OSV) |
| opensuse:httpcomponents-client | 4.5.14-2.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| suse:httpcomponents-client | 4.5.14-150200.3.12.1 · SUSE:Linux Enterprise Module for Development Tools 15 SP7 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
- Yu BaoPaypalfinder
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- low · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- Low
Weakness class (CWE)
CWE-772 · Missing Release of Resource after Effective LifetimeCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- lists.apache.org/thread/qqfzo3fqcdk4l5496vz95ppvl4ty511q
- www.openwall.com/lists/oss-security/2026/08/13/5
Vendor advisories and official records. Exploit/PoC links are deliberately left out.