Evidence used
- No CISA KEV confirmation is currently recorded.
- The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
- EPSS is 0.76% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-110354High confidence
HAProxy 3 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (persistent worker-thread CPU exhaustion) via an HTTP/1.1 chunked request
HAProxy · HAProxy
7.5HighCVSS 3.1
Within 7 days
Fix not verifiedHigh technical severity; prioritise exposed affected systems while verifying vendor guidance.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:High, unchanged from published severity.unchanged
Compensating controls
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs HAProxy HAProxy and falls inside the recorded affected range.
- Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Distribution package intelligence
1 package stateRelease-specific package status
ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
| Distribution release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Ubuntu 24.04 LTSnoble · standard archive | haproxy | Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 23 Oct 2026 |
Direct vendor intelligence
2 currentAuthoritative vendor CSAF and VEX advisories
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
CVE-2026-110354 · CSAF 2.0 · revision 2 · interimSUSE Product Security TeamCVE-2026-110354
The vendor explicitly identifies these products as affected by this CVE.
- haproxy as component of SUSE Linux Enterprise High Availability Extension 12 SP5
- haproxy as component of SUSE Linux Enterprise High Availability Extension 15 SP4
- haproxy as component of SUSE Linux Enterprise High Availability Extension 15 SP5
- haproxy as component of SUSE Linux Enterprise High Availability Extension 15 SP7
- haproxy as component of SUSE Linux Enterprise High Availability Extension 16.0
- haproxy as component of SUSE Linux Enterprise Micro 5.3
- haproxy as component of SUSE Linux Enterprise Micro 5.4
- haproxy as component of SUSE Linux Enterprise Micro 5.5
- haproxy as component of SUSE Linux Enterprise Server 16.1
- haproxy as component of SUSE Linux Enterprise Server for SAP Applications 12 SP5
- haproxy as component of SUSE Linux Enterprise Server for SAP applications 16.0
- haproxy as component of SUSE Linux Enterprise Server for SAP applications 16.1
- Summary
- HAProxy 3 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (persistent worker-thread CPU exhaustion) via an HTTP/1.1 chunked request. Although the H1 multiplexer drains the request before closing the stream, the parser repeatedly re-processes the same bytes without making progress. The affected thread stays busy at 100% CPU after timeouts expire and after the client disconnects, and repeated requests can consume all worker threads until the process is restarted.
- Remediation
- No remediation text is recorded.
CVE-2026-110354 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityhaproxy: haproxy: Denial of Service via specially crafted HTTP/1.1 chunked request
The vendor explicitly identifies these products as affected by this CVE.
- haproxy.src as a component of Red Hat Ceph Storage 5
- haproxy22 as a component of Red Hat Ceph Storage 5
- haproxy as a component of Red Hat Enterprise Linux 10
- haproxy.src as a component of Red Hat Enterprise Linux 10
- haproxy as a component of Red Hat Enterprise Linux 7
- haproxy.src as a component of Red Hat Enterprise Linux 7
- haproxy as a component of Red Hat Enterprise Linux 8
- haproxy.src as a component of Red Hat Enterprise Linux 8
- haproxy as a component of Red Hat Enterprise Linux 9
- haproxy.src as a component of Red Hat Enterprise Linux 9
- haproxy.src as a component of Red Hat Hardened Images
- haproxy.src as a component of Red Hat OpenShift Container Platform 4
- Summary
- A flaw was found in haproxy. A remote, unauthenticated attacker can trigger a denial of service (DoS) by sending a specially crafted HTTP/1.1 chunked request. When processing the request, the parser repeatedly re-evaluates the same data without making forward progress, trapping the worker thread in a continuous loop that consumes 100% CPU. Multiple malicious requests can exhaust all worker threads, rendering the proxy completely unresponsive until restarted.
- Remediation
- Fix deferred
High technical severity; prioritise exposed affected systems while verifying vendor guidance.
Fix not verified01
What, why and how
HAProxy 3 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (persistent worker-thread CPU exhaustion) via an HTTP/1.1 chunked request. Although the H1 multiplexer drains the request before closing the stream, the parser repeatedly re-processes the same bytes without making progress. The affected thread stays busy at 100% CPU after timeouts expire and after the client disconnects, and repeated requests can consume all worker threads until the process is restarted.
What
HAProxy 3 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (persistent worker-thread CPU exhaustion) via an HTTP/1.1 chunked request. Although the H1 multiplexer drains the request before closing the stream, the parser repeatedly re-processes the same bytes without making progress. The affected thread stays busy at 100% CPU after timeouts expire and after the client disconnects, and repeated requests can consume all worker threads until the process is restarted.
Why
A malformed condition prevents a loop from making progress or terminating, allowing resource exhaustion.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.
What
HAProxy 3 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (persistent worker-thread CPU exhaustion) via an HTTP/1.1 chunked request. Although the H1 multiplexer drains the request before closing the stream, the parser repeatedly re-processes the same bytes without making progress. The affected thread stays busy at 100% CPU after timeouts expire and after the client disconnects, and repeated requests can consume all worker threads until the process is restarted.
Why
A malformed condition prevents a loop from making progress or terminating, allowing resource exhaustion.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- a network path → Loop with Unreachable Exit Condition ('Infinite Loop') → disrupt the affected service
- Attack surface
- Network
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-835 ↗
CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop'). The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.- Post-exploitation / living off the land
- No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Fix not verified
- Affected
- haproxy as component of SUSE Linux Enterprise High Availability Extension 12 SP5
- haproxy as component of SUSE Linux Enterprise High Availability Extension 15 SP4
- haproxy as component of SUSE Linux Enterprise High Availability Extension 15 SP5
- haproxy as component of SUSE Linux Enterprise High Availability Extension 15 SP7
- haproxy as component of SUSE Linux Enterprise High Availability Extension 16.0
- haproxy as component of SUSE Linux Enterprise Micro 5.3
- haproxy as component of SUSE Linux Enterprise Micro 5.4
- haproxy as component of SUSE Linux Enterprise Micro 5.5
- haproxy as component of SUSE Linux Enterprise Server 16.1
- haproxy as component of SUSE Linux Enterprise Server for SAP Applications 12 SP5
- haproxy as component of SUSE Linux Enterprise Server for SAP applications 16.0
- haproxy as component of SUSE Linux Enterprise Server for SAP applications 16.1
- haproxy as component of SUSE Linux Micro 6.0
- haproxy as component of SUSE Linux Micro 6.1
- haproxy as component of SUSE Linux Micro 6.2
- haproxy as component of openSUSE Leap 16.0
- haproxy as component of openSUSE Leap 16.1
- Fixed
- No fixed version is explicitly recorded in the structured CVE data.
- Action
- No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
- Workaround
- No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 22 Oct 2026 · Last source change 22 Oct 2026, 19:10 UTC · CWE-835 · Loop with Unreachable Exit Condition ('Infinite Loop')
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-10-22
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-108000
Product sourceVendor CSAF · SUSE Product Security Team
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD awaiting enrichment
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- ENISA EUVD mappingEUVD-2026-108000 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2026-108000"}
- Vendor guidanceAuthoritative vendor guidance changed from remediation: access.redhat.com/CVE-2026-110354 to remediation: access.redhat.com/CVE-2026-110354.Red Hat Product Security ↗
- Before
- remediation: access.redhat.com/CVE-2026-110354
- After
- remediation: access.redhat.com/CVE-2026-110354
- Vendor guidanceAuthoritative vendor guidance changed: removed vendor advisory: git.haproxy.org?p=haproxy.git;a=commit;h=077906da140a35873bf451d7e9f67646c9f37c81.CNA ↗
- Before
- vendor advisory: git.haproxy.org?p=haproxy.git;a=commit;h=077906da140a35873bf451d7e9f67646c9f37c81
- After
- no authoritative guidance recorded
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.