Apache Tomcat: DoS via busy wait during WebSocket close
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 5 fixed, 5 without a fix
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat. Impact type from CWE-400.
Summary
Uncontrolled Resource Consumption vulnerability in Apache Tomcat during sending of WebSocket close message enabled a DoS attack. This issue affects Apache Tomcat: from 11.0.0-M5 through 11.0.25, from 10.1.8 through 10.1.59, from 9.0.74 through 9.0.121. The following versions were EOL at the time the CVE was created but are known to be affected: from 8.5.88 through 8.5.100. Other unsupported versions may also be affected. Users are recommended to upgrade to version 11.0.26, 10.1.60 or 9.0.122, which fix the issue.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Apache | Apache Tomcat | 11.0.0-M5 – 11.0.25; 10.1.8 – 10.1.59; 9.0.74 – 9.0.121; 8.5.88 – 8.5.100 | — | Patch available | CNA |
- Apache Tomcat VendorApache Affected 11.0.0-M5 – 11.0.25; 10.1.8 – 10.1.59; 9.0.74 – 9.0.121; 8.5.88 – 8.5.100 Fixed in — Patch available CNA
Remediation
Red Hat 4 advisories
- RHSA-2026:93618 Released 2026-11-03 · Red Hat rating ImportantRed Hat JBoss Web Server 7.0.3 release and security update
- Red Hat JBoss Web Server 7.0 on RHEL 10 jws7-mod_cluster-2.1.1-1.Final_redhat_00001.1.el10jws, jws7-mod_cluster-tomcat-2.1.1-1.Final_redhat_00001.1.el10jws, jws7-tomcat-11.0.21-10.redhat_00010.1.el10jws +10
- Red Hat JBoss Web Server 7.0 on RHEL 8 jws7-mod_cluster-2.1.1-1.Final_redhat_00001.1.el8jws, jws7-mod_cluster-tomcat-2.1.1-1.Final_redhat_00001.1.el8jws, jws7-tomcat-11.0.21-10.redhat_00010.1.el8jws +10
- Red Hat JBoss Web Server 7.0 on RHEL 9 jws7-mod_cluster-2.1.1-1.Final_redhat_00001.1.el9jws, jws7-mod_cluster-tomcat-2.1.1-1.Final_redhat_00001.1.el9jws, jws7-tomcat-11.0.21-10.redhat_00010.1.el9jws +10
- RHSA-2026:93622 Released 2026-11-03 · Red Hat rating ImportantRed Hat JBoss Web Server 7.0.3 release and security update
- Red Hat JBoss Web Server 7.0.3
- RHSA-2026:68258 Released 2026-09-16 · Red Hat rating ImportantRed Hat Hardened Images RPMs bug fix and enhancement update
- Red Hat Hardened Images tomcat11-1:11.0.26-0.1.hum1@noarch@public-hummingbird-aarch64-rpms, tomcat11-1:11.0.26-0.1.hum1@noarch@public-hummingbird-x86_64-rpms, tomcat11-1:11.0.26-0.1.hum1@src +18
Show 1 more Red Hat advisories
- RHSA-2026:68257 Released 2026-09-16 · Red Hat rating ImportantRed Hat Hardened Images RPMs bug fix and enhancement update
- Red Hat Hardened Images tomcat10-1:10.1.60-0.1.hum1@noarch@public-hummingbird-aarch64-rpms, tomcat10-1:10.1.60-0.1.hum1@noarch@public-hummingbird-x86_64-rpms, tomcat10-1:10.1.60-0.1.hum1@src +18
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet |
| Red Hat Enterprise Linux 8 | Affected | No fix yet |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
| Red Hat JBoss Web Server 5 | Affected | No fix planned: Will not fix |
| Red Hat JBoss Web Server 6 | Affected | No fix yet |
| Red Hat Hardened Images | Fixed | RHSA-2026:68257, RHSA-2026:68258 |
| Red Hat JBoss Web Server 7.0 on RHEL 10 | Fixed | RHSA-2026:93618 |
| Red Hat JBoss Web Server 7.0 on RHEL 8 | Fixed | RHSA-2026:93618 |
| Red Hat JBoss Web Server 7.0 on RHEL 9 | Fixed | RHSA-2026:93618 |
| Red Hat JBoss Web Server 7.0.3 | Fixed | RHSA-2026:93622 |
Not affected: 5 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat Hardened Images
Timeline
- 2026-10-02 Threatist record created from CVE-2026-77791
- 2026-10-03 Alias added: GHSA-9cg7-2q68-g3mq
- 2026-10-25 EPSS moved to the 50th–90th percentile
- 2026-10-25 Priority changed: LOW → MEDIUM
- 2026-11-03 Fix available: RHSA-2026:93622 · Red Hat
- 2026-11-03 Fix available: RHSA-2026:93618 · Red Hat
- 2026-11-03 Fix available: Red Hat JBoss Web Server 7.0 on RHEL 10, Red Hat JBoss Web Server 7.0 on RHEL 8, Red Hat JBoss Web Server 7.0 on RHEL 9 +1 · Red Hat
References
More Apache vulnerabilities
- TI-2025-18529 Apache Tomcat: Potential RCE and/or information disclosure and/or information corruption with partial PUT KEVCVSS 3.1CRITICAL 10.0
- TI-2024-30292 Apache OFBiz: Confused controller-view authorization logic (forced browsing) KEVCVSS 3.1CRITICAL 9.8
- TI-2024-26062 Apache OFBiz: Unauthenticated endpoint could allow execution of screen rendering code KEVCVSS 3.1CRITICAL 9.8
- TI-2024-21190 Apache OFBiz: Path traversal leading to RCE KEVCVSS 3.1CRITICAL 9.8
- TI-2024-18186 Apache HugeGraph-Server: Command execution in gremlin KEVCVSS 3.1CRITICAL 9.8
- TI-2023-25106 Deserialization of untrusted data in Apache ActiveMQ KEVCVSS 3.1CRITICAL 10.0
Sources
- CVE-2026-77791 · CVE Program
- CVE-2026-77791 · NVD
- FIRST EPSS
- GHSA-9cg7-2q68-g3mq · GitHub Advisory Database · CC BY 4.0
- CVE-2026-77791 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences