EUVD-2026-66190
GHSA-82jr-6mfr-9vq5
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Network-reachable DoS requiring no authentication or interaction; AC:L because sending RST_STREAM is a standard HTTP/2 operation with no special preconditions beyond connectivity.
Primary rating from Vendor (apache).
CVSS VectorVendor: apache
Lifecycle Timeline
4DescriptionCVE.org
Uncontrolled Resource Consumption vulnerability in Apache Tomcat via an allocation leak in the HTTP/2 backlog tracking when a stream is reset
This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.24, from 10.1.0-M1 through 10.1.57, from 9.0.39 through 9.0.120.
The following versions were EOL at the time the CVE was created but are known to be affected: from 8.5.59 through 8.5.100. Other unsupported versions may also be affected.
Users are recommended to upgrade to version 11.0.25, 10.1.58 or 9.0.121, which fix the issue.
AnalysisAI
Uncontrolled resource consumption in Apache Tomcat's HTTP/2 implementation allows remote unauthenticated attackers to exhaust server memory by repeatedly opening and resetting HTTP/2 streams, exploiting an allocation leak in the backlog tracking mechanism that fails to release memory on stream reset. Affected branches span Tomcat 9.0.39-9.0.120, 10.1.0-M1-10.1.57, and 11.0.0-M1-11.0.24, with EOL branch 8.5.59-8.5.100 also confirmed vulnerable but unpatchable. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires that HTTP/2 is explicitly enabled on the target Tomcat connector via the UpgradeProtocol element (class='org.apache.coyote.http2.Http2Protocol') in server.xml - this is not enabled in all default Tomcat configurations and typically requires TLS to be configured as a prerequisite. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) confirms a maximally accessible network-exploitable DoS - no authentication, no complexity, no user interaction required - yielding a 7.5 HIGH score. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | The Apache Software Foundation has released patches in versions 11.0.25, 10.1.58, and 9.0.121, each of which resolves the allocation leak in HTTP/2 backlog tracking. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all Apache Tomcat deployments to identify instances running versions 9.0.39-9.0.120, 10.1.0-M1-10.1.57, or 11.0.0-M1-11.0.24; immediately disable HTTP/2 protocol support or implement rate limiting on stream connections. …
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Same weakness CWE-400 – Uncontrolled Resource Consumption
View allSame technique Denial Of Service
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External POC / Exploit Code
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