Infinite loop in Apache Tomcat
Priority MEDIUM 49CWE-835Published · Updated
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: 1 without a fix
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-835.
Summary
The HTTP/2 header parser in Apache Tomcat 9.0.0.M1 to 9.0.0.M11 and 8.5.0 to 8.5.6 entered an infinite loop if a header was received that was larger than the available buffer. This made a denial of service attack possible.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0719 94th percentileScored 2026-11-07
Fix Partial org.apache.tomcat:tomcat (Maven): 9.0.0.M12, 8.5.8Red Hat: 1 without a fix
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 | 9.0.0.M1 to 9.0.0.M11; 8.5.0 to 8.5.6 | — | No fix listed | CNA |
| — | org.apache.tomcat:tomcat (Maven) | 9.0.0.M1 to before 9.0.0.M12 | 9.0.0.M12 | Patch available | GHSA-698c-2x4j-g9gq |
| — | org.apache.tomcat:tomcat (Maven) | 8.5.0 to before 8.5.8 | 8.5.8 | Patch available | GHSA-698c-2x4j-g9gq |
- Apache Tomcat VendorApache Affected 9.0.0.M1 to 9.0.0.M11; 8.5.0 to 8.5.6 Fixed in — No fix listed CNA
- org.apache.tomcat:tomcat (Maven) Vendor— Affected 9.0.0.M1 to before 9.0.0.M12 Fixed in 9.0.0.M12 Patch available GHSA-698c-2x4j-g9gq
- org.apache.tomcat:tomcat (Maven) Vendor— Affected 8.5.0 to before 8.5.8 Fixed in 8.5.8 Patch available GHSA-698c-2x4j-g9gq
CPE configurations NVD · 18
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:apache:tomcat:8.5.0:*:*:*:*:*:*:* | 8.5.0 | Vulnerable | Apache |
| cpe:2.3:a:apache:tomcat:8.5.1:*:*:*:*:*:*:* | 8.5.1 | Vulnerable | Apache |
| cpe:2.3:a:apache:tomcat:8.5.2:*:*:*:*:*:*:* | 8.5.2 | Vulnerable | Apache |
| cpe:2.3:a:apache:tomcat:8.5.3:*:*:*:*:*:*:* | 8.5.3 | Vulnerable | Apache |
| cpe:2.3:a:apache:tomcat:8.5.4:*:*:*:*:*:*:* | 8.5.4 | Vulnerable | Apache |
| cpe:2.3:a:apache:tomcat:8.5.5:*:*:*:*:*:*:* | 8.5.5 | Vulnerable | Apache |
| cpe:2.3:a:apache:tomcat:8.5.6:*:*:*:*:*:*:* | 8.5.6 | Vulnerable | Apache |
| cpe:2.3:a:apache:tomcat:9.0.0:milestone1:*:*:*:*:*:* | 9.0.0 milestone1 | Vulnerable | Apache |
| cpe:2.3:a:apache:tomcat:9.0.0:milestone10:*:*:*:*:*:* | 9.0.0 milestone10 | Vulnerable | Apache |
| cpe:2.3:a:apache:tomcat:9.0.0:milestone11:*:*:*:*:*:* | 9.0.0 milestone11 | Vulnerable | Apache |
- cpe:2.3:a:apache:tomcat:8.5.0:*:*:*:*:*:*:* Versions 8.5.0 Vulnerable ·Apache
- cpe:2.3:a:apache:tomcat:8.5.1:*:*:*:*:*:*:* Versions 8.5.1 Vulnerable ·Apache
- cpe:2.3:a:apache:tomcat:8.5.2:*:*:*:*:*:*:* Versions 8.5.2 Vulnerable ·Apache
- cpe:2.3:a:apache:tomcat:8.5.3:*:*:*:*:*:*:* Versions 8.5.3 Vulnerable ·Apache
- cpe:2.3:a:apache:tomcat:8.5.4:*:*:*:*:*:*:* Versions 8.5.4 Vulnerable ·Apache
- cpe:2.3:a:apache:tomcat:8.5.5:*:*:*:*:*:*:* Versions 8.5.5 Vulnerable ·Apache
- cpe:2.3:a:apache:tomcat:8.5.6:*:*:*:*:*:*:* Versions 8.5.6 Vulnerable ·Apache
- cpe:2.3:a:apache:tomcat:9.0.0:milestone1:*:*:*:*:*:* Versions 9.0.0 milestone1 Vulnerable ·Apache
- cpe:2.3:a:apache:tomcat:9.0.0:milestone10:*:*:*:*:*:* Versions 9.0.0 milestone10 Vulnerable ·Apache
- cpe:2.3:a:apache:tomcat:9.0.0:milestone11:*:*:*:*:*:* Versions 9.0.0 milestone11 Vulnerable ·Apache
Show 8 more CPE
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:apache:tomcat:9.0.0:milestone2:*:*:*:*:*:* | 9.0.0 milestone2 | Vulnerable | Apache |
| cpe:2.3:a:apache:tomcat:9.0.0:milestone3:*:*:*:*:*:* | 9.0.0 milestone3 | Vulnerable | Apache |
| cpe:2.3:a:apache:tomcat:9.0.0:milestone4:*:*:*:*:*:* | 9.0.0 milestone4 | Vulnerable | Apache |
| cpe:2.3:a:apache:tomcat:9.0.0:milestone5:*:*:*:*:*:* | 9.0.0 milestone5 | Vulnerable | Apache |
| cpe:2.3:a:apache:tomcat:9.0.0:milestone6:*:*:*:*:*:* | 9.0.0 milestone6 | Vulnerable | Apache |
| cpe:2.3:a:apache:tomcat:9.0.0:milestone7:*:*:*:*:*:* | 9.0.0 milestone7 | Vulnerable | Apache |
| cpe:2.3:a:apache:tomcat:9.0.0:milestone8:*:*:*:*:*:* | 9.0.0 milestone8 | Vulnerable | Apache |
| cpe:2.3:a:apache:tomcat:9.0.0:milestone9:*:*:*:*:*:* | 9.0.0 milestone9 | Vulnerable | Apache |
- cpe:2.3:a:apache:tomcat:9.0.0:milestone2:*:*:*:*:*:* Versions 9.0.0 milestone2 Vulnerable ·Apache
- cpe:2.3:a:apache:tomcat:9.0.0:milestone3:*:*:*:*:*:* Versions 9.0.0 milestone3 Vulnerable ·Apache
- cpe:2.3:a:apache:tomcat:9.0.0:milestone4:*:*:*:*:*:* Versions 9.0.0 milestone4 Vulnerable ·Apache
- cpe:2.3:a:apache:tomcat:9.0.0:milestone5:*:*:*:*:*:* Versions 9.0.0 milestone5 Vulnerable ·Apache
- cpe:2.3:a:apache:tomcat:9.0.0:milestone6:*:*:*:*:*:* Versions 9.0.0 milestone6 Vulnerable ·Apache
- cpe:2.3:a:apache:tomcat:9.0.0:milestone7:*:*:*:*:*:* Versions 9.0.0 milestone7 Vulnerable ·Apache
- cpe:2.3:a:apache:tomcat:9.0.0:milestone8:*:*:*:*:*:* Versions 9.0.0 milestone8 Vulnerable ·Apache
- cpe:2.3:a:apache:tomcat:9.0.0:milestone9:*:*:*:*:*:* Versions 9.0.0 milestone9 Vulnerable ·Apache
Remediation
- Fix · GHSA-698c-2x4j-g9gq org.apache.tomcat:tomcat (Maven) Fixed in 9.0.0.M12 Advisory →
- Fix · GHSA-698c-2x4j-g9gq org.apache.tomcat:tomcat (Maven) Fixed in 8.5.8 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Software Collections | Affected | — |
Not affected: 6 products
- Red Hat JBoss Enterprise Application Platform 5
- Red Hat JBoss Enterprise Application Platform 6
- Red Hat JBoss Enterprise Application Platform 7
- Red Hat JBoss Enterprise Web Server 2
- Red Hat JBoss Enterprise Web Server 3
- Red Hat JBoss Web Server 3
Timeline
- 2026-10-02 Threatist record created from CVE-2016-6817
- 2026-10-03 Alias added: GHSA-698c-2x4j-g9gq
References
Other 17
- [announce] 20161122 [SECURITY] CVE-2016-6817 Apache Tomcat Denial of Service
- https://security.netapp.com/advisory/ntap-20180607-0001/
- [tomcat-dev] 20190319 svn commit: r1855831 [25/30] - in /tomcat/site/trunk: ./ docs/ xdocs/
- [tomcat-dev] 20190325 svn commit: r1856174 [24/29] - in /tomcat/site/trunk: docs/ xdocs/ xdocs/stylesheets/
- [tomcat-dev] 20190413 svn commit: r1857494 [17/20] - in /tomcat/site/trunk: ./ docs/ xdocs/
- [tomcat-dev] 20190415 svn commit: r1857582 [19/22] - in /tomcat/site/trunk: docs/ xdocs/stylesheets/
- https://github.com/apache/tomcat/commit/079372fc7bac8e2e378942715c9ce26a4a72c07a
- https://github.com/apache/tomcat/commit/85c63227edabbfb4f2f500fc557480a190135d21
- https://web.archive.org/web/20200227174145/http://www.securityfocus.com/bid/94462
- https://web.archive.org/web/20180115024458/http://www.securitytracker.com/id/1037330
- https://security.netapp.com/advisory/ntap-20180607-0001
- https://lists.apache.org/thread.html/b5e3f51d28cd5d9b1809f56594f2cf63dcd6a90429e16ea9f83bbedc@%3Cdev.tomcat.apache.org%3E
- https://lists.apache.org/thread.html/a9f24571460af003071475b75f18cad81ebcc36fa7c876965a75e32a@%3Cannounce.tomcat.apache.org%3E
- https://lists.apache.org/thread.html/88855876c33f2f9c532ffb75bfee570ccf0b17ffa77493745af9a17a@%3Cdev.tomcat.apache.org%3E
- https://lists.apache.org/thread.html/6af47120905aa7d8fe12f42e8ff2284fb338ba141d3b77b8c7cb61b3@%3Cdev.tomcat.apache.org%3E
- https://lists.apache.org/thread.html/343558d982879bf88ec20dbf707f8c11255f8e219e81d45c4f8d0551@%3Cdev.tomcat.apache.org%3E
- https://github.com/apache/tomcat
More Apache Tomcat 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-2020-01862 Improper privilege management in Apache Tomcat KEVCVSS 3.1CRITICAL 9.8
- TI-2016-07192 Improper access control in Apache Tomcat KEVCVSS 3.1CRITICAL 9.8
- TI-2017-09342 Unrestricted file upload in Apache Tomcat KEVCVSS 3.1HIGH 8.1
- TI-2017-09340 Unrestricted file upload in Apache Tomcat KEVCVSS 3.1HIGH 8.1
- TI-2026-26741 Apache Tomcat: Fix for CVE-2026-29146 allowed bypass of EncryptInterceptor KEVCVSS 3.1HIGH 7.5
Sources
- CVE-2016-6817 · CVE Program
- CVE-2016-6817 · NVD
- FIRST EPSS
- GHSA-698c-2x4j-g9gq · GitHub Advisory Database · CC BY 4.0
- CVE-2016-6817 · 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