Apache Tomcat has an Always-Incorrect Control Flow Implementation vulnerability

Apache Tomcat

Always-Incorrect Control Flow Implementation vulnerability in Apache Tomcat meant that special roles and empty authorisation constraints were not included when the effective web.xml was logged.

Fixed for Java (org.apache.tomcat.embed:tomcat-embed-core), Java (org.apache.tomcat:tomcat) and Java (org.apache.tomcat:tomcat-util-scan); still cooking for Apache Tomcat.

First seen: 29 Jun 2026
Last update: 29 Jun 2026, 21:32 UTC
Versions per GitHub advisory, not the vendor: org.apache.tomcat.embed:tomcat-embed-core 11.0.23
org.apache.tomcat.embed:tomcat-embed-core 10.1.56
org.apache.tomcat.embed:tomcat-embed-core 9.0.119
org.apache.tomcat:tomcat 11.0.23
org.apache.tomcat:tomcat 10.1.56
org.apache.tomcat:tomcat 9.0.119
org.apache.tomcat:tomcat-util-scan 11.0.23
org.apache.tomcat:tomcat-util-scan 10.1.56
org.apache.tomcat:tomcat-util-scan 9.0.119
Identifiers: CVE-2026-55276
CVSS: 9.1
Source: GitHub advisory
On the menu as: Java

Check this repository for exposure to one security incident from pwned.coffee. Report first, change nothing until I say so.

## Apache Tomcat has an Always-Incorrect Control Flow Implementation vulnerability
Severity: critical. Patch status: fix status unknown.
Affected: Apache Tomcat
Versions per GitHub advisory, not the vendor: org.apache.tomcat.embed:tomcat-embed-core 11.0.23, org.apache.tomcat.embed:tomcat-embed-core 10.1.56, org.apache.tomcat.embed:tomcat-embed-core 9.0.119, org.apache.tomcat:tomcat 11.0.23, org.apache.tomcat:tomcat 10.1.56, org.apache.tomcat:tomcat 9.0.119, org.apache.tomcat:tomcat-util-scan 11.0.23, org.apache.tomcat:tomcat-util-scan 10.1.56, org.apache.tomcat:tomcat-util-scan 9.0.119
Ids: CVE-2026-55276

Always-Incorrect Control Flow Implementation vulnerability in Apache Tomcat meant that special roles and empty authorisation constraints were not included when the effective web.xml was logged.

## Steps
1. Search every lockfile and manifest (package-lock.json, yarn.lock, pnpm-lock.yaml, requirements*.txt, poetry.lock, uv.lock, composer.lock, go.sum, Cargo.lock, Gemfile.lock) for `org.apache.tomcat.embed:tomcat-embed-core`, `org.apache.tomcat:tomcat`, `org.apache.tomcat:tomcat-util-scan`. For each hit, compare the installed version with the version on the same major line (per GitHub advisory, not the vendor, so check the vendor's advisory before treating it as a fix): org.apache.tomcat.embed:tomcat-embed-core 11.0.23, org.apache.tomcat.embed:tomcat-embed-core 10.1.56, org.apache.tomcat.embed:tomcat-embed-core 9.0.119, org.apache.tomcat:tomcat 11.0.23, org.apache.tomcat:tomcat 10.1.56, org.apache.tomcat:tomcat 9.0.119, org.apache.tomcat:tomcat-util-scan 11.0.23, org.apache.tomcat:tomcat-util-scan 10.1.56, org.apache.tomcat:tomcat-util-scan 9.0.119. If it's lower, give the exact upgrade command for the package manager this repo uses.
2. Versions per GitHub advisory, not the vendor: org.apache.tomcat.embed:tomcat-embed-core: 11.0.x → 11.0.23; 10.1.x → 10.1.56; 9.0.x → 9.0.119. org.apache.tomcat:tomcat: 11.0.x → 11.0.23; 10.1.x → 10.1.56; 9.0.x → 9.0.119. org.apache.tomcat:tomcat-util-scan: 11.0.x → 11.0.23; 10.1.x → 10.1.56; 9.0.x → 9.0.119. Don't treat them as a fix until the vendor says so. org.apache.tomcat.embed:tomcat-embed-core 8.5.x; org.apache.tomcat:tomcat 8.5.x; org.apache.tomcat:tomcat-util-scan 8.5.x: no fixed version listed, per GitHub advisory, not the vendor. Apache Tomcat 11.0.x, 10.1.x, 9.0.x, 8.5.x: the CVE record names no fix; check the vendor advisory before assuming there is none. Until one ships: restrict network access to it.

## Fix by release line
| Line | State | Fix | Until then |
|---|---|---|---|
| org.apache.tomcat.embed:tomcat-embed-core 11.0.x | per GitHub advisory, not the vendor | 11.0.23 | restrict network access to it |
| org.apache.tomcat.embed:tomcat-embed-core 10.1.x | per GitHub advisory, not the vendor | 10.1.56 | restrict network access to it |
| org.apache.tomcat.embed:tomcat-embed-core 9.0.x | per GitHub advisory, not the vendor | 9.0.119 | restrict network access to it |
| org.apache.tomcat.embed:tomcat-embed-core 8.5.x | per GitHub advisory, not the vendor | no fixed version listed | restrict network access to it |
| org.apache.tomcat:tomcat 11.0.x | per GitHub advisory, not the vendor | 11.0.23 | restrict network access to it |
| org.apache.tomcat:tomcat 10.1.x | per GitHub advisory, not the vendor | 10.1.56 | restrict network access to it |
| org.apache.tomcat:tomcat 9.0.x | per GitHub advisory, not the vendor | 9.0.119 | restrict network access to it |
| org.apache.tomcat:tomcat 8.5.x | per GitHub advisory, not the vendor | no fixed version listed | restrict network access to it |
| org.apache.tomcat:tomcat-util-scan 11.0.x | per GitHub advisory, not the vendor | 11.0.23 | restrict network access to it |
| org.apache.tomcat:tomcat-util-scan 10.1.x | per GitHub advisory, not the vendor | 10.1.56 | restrict network access to it |
| org.apache.tomcat:tomcat-util-scan 9.0.x | per GitHub advisory, not the vendor | 9.0.119 | restrict network access to it |
| org.apache.tomcat:tomcat-util-scan 8.5.x | per GitHub advisory, not the vendor | no fixed version listed | restrict network access to it |
| Apache Tomcat 8.5 to 11.0 (4 lines) | not named in the CVE record | check the vendor advisory | restrict network access to it |

## Report
A table: file, product or package, version in use, affected yes/no, exact fix. Then anything a human has to check outside the repo.

If you have the pwned.coffee MCP server (https://pwned.coffee/mcp), call lookup_cve("CVE-2026-55276") for the latest, and check_repo with this repo's lockfiles, Dockerfiles and workflows for a full receipt.
Sources: http://www.openwall.com/lists/oss-security/2026/06/29/23 https://github.com/advisories/GHSA-mqg3-r7h5-24x4 https://github.com/apache/tomcat/commit/3ca8cae5fd3796b1bd9759e11b0e238161e7a39c https://lists.apache.org/thread/jy09xjlzn6r2qwvqoph8vcmf959yq68v https://nvd.nist.gov/vuln/detail/CVE-2026-55276
https://pwned.coffee/i/apache-tomcat-has-an-always-incorrect-control-flow-imple-cve-2026-55276

Receipt

Exploitation: No known exploitation
By release line, per GitHub advisory, not the vendor: Product Affected Version named Source
org.apache.tomcat.embed:tomcat-embed-core (maven) >= 11.0.0-M1, < 11.0.23 11.0.23 GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat.embed:tomcat-embed-core (maven) >= 10.1.0-M1, < 10.1.56 10.1.56 GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat.embed:tomcat-embed-core (maven) >= 9.0.0.M1, < 9.0.119 9.0.119 GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat.embed:tomcat-embed-core (maven) >= 8.5.0, <= 8.5.100 no fix on 8.x yet; move to 9.0.119+ (newer branch) GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat:tomcat (maven) >= 11.0.0-M1, < 11.0.23 11.0.23 GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat:tomcat (maven) >= 10.1.0-M1, < 10.1.56 10.1.56 GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat:tomcat (maven) >= 9.0.0.M1, < 9.0.119 9.0.119 GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat:tomcat (maven) >= 8.5.0, <= 8.5.100 no fix on 8.x yet; move to 9.0.119+ (newer branch) GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat:tomcat-util-scan (maven) >= 11.0.0-M1, < 11.0.23 11.0.23 GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat:tomcat-util-scan (maven) >= 10.1.0-M1, < 10.1.56 10.1.56 GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat:tomcat-util-scan (maven) >= 9.0.0.M1, < 9.0.119 9.0.119 GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat:tomcat-util-scan (maven) >= 8.5.0, <= 8.5.100 no fix on 8.x yet; move to 9.0.119+ (newer branch) GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
Score: CVSS 9.1 (critical). CVSS 3.1 9.1 (CISA ADP) for CVE-2026-55276
Last checked: 4 Nov 2026, 17:17 UTC

Product	Affected	Version named	Source
org.apache.tomcat.embed:tomcat-embed-core (maven)	>= 11.0.0-M1, < 11.0.23	11.0.23	GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat.embed:tomcat-embed-core (maven)	>= 10.1.0-M1, < 10.1.56	10.1.56	GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat.embed:tomcat-embed-core (maven)	>= 9.0.0.M1, < 9.0.119	9.0.119	GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat.embed:tomcat-embed-core (maven)	>= 8.5.0, <= 8.5.100	no fix on 8.x yet; move to 9.0.119+ (newer branch)	GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat:tomcat (maven)	>= 11.0.0-M1, < 11.0.23	11.0.23	GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat:tomcat (maven)	>= 10.1.0-M1, < 10.1.56	10.1.56	GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat:tomcat (maven)	>= 9.0.0.M1, < 9.0.119	9.0.119	GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat:tomcat (maven)	>= 8.5.0, <= 8.5.100	no fix on 8.x yet; move to 9.0.119+ (newer branch)	GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat:tomcat-util-scan (maven)	>= 11.0.0-M1, < 11.0.23	11.0.23	GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat:tomcat-util-scan (maven)	>= 10.1.0-M1, < 10.1.56	10.1.56	GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat:tomcat-util-scan (maven)	>= 9.0.0.M1, < 9.0.119	9.0.119	GitHub advisory per GitHub advisory, not the vendor checked 4 Nov
org.apache.tomcat:tomcat-util-scan (maven)	>= 8.5.0, <= 8.5.100	no fix on 8.x yet; move to 9.0.119+ (newer branch)	GitHub advisory per GitHub advisory, not the vendor checked 4 Nov

Sources: KEV – CVE record ✓ Vendor –

Sources

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