CVE-2026-18047
Description
A flaw was found in Dogtag PKI's ACME responder where the web.xml security constraints use exact URL pattern matching for admin-only enable/disable endpoints. By appending a trailing slash to the URL, an unauthenticated attacker can bypass the Tomcat authentication constraint while RESTEasy still routes the request to the handler, allowing unauthorized toggling of the ACME service state including persistent denial of service.
Statement
Red Hat rates this as Moderate because the impact of the authentication bypass is limited in scope and consequence. The vulnerability only affects the ACME enable/disable admin endpoints — other PKI subsystems (CA, KRA, OCSP, TPS) enforce authorization at the application layer and are not affected by this flaw. An attacker who exploits this flaw can only toggle the ACME service on or off. While re-enabling a disabled ACME service restores the full ACME protocol stack, certificate issuance through ACME still requires completing the standard RFC 8555 challenge-response flow, including proof of domain control — the enable/disable bypass alone does not grant the ability to obtain certificates. The ACME responder requires explicit installation and deployment and is not present in default PKI server configurations.
Mitigation
To mitigate this vulnerability, change the URL patterns in the ACME responder's web.xml from exact-match to prefix-match.
Edit the file /usr/share/pki/acme/webapps/acme/WEB-INF/web.xml and replace the url-pattern entries for the enable and disable endpoints:
<url-pattern>/enable</url-pattern> -> <url-pattern>/enable/*</url-pattern>
<url-pattern>/disable</url-pattern> -> <url-pattern>/disable/*</url-pattern>
Then restart the PKI server for the changes to take effect.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.5 | N/A | 6.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | Low | N/A | Low |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
Understanding the Weakness (CWE)
Access Control
Technical Impact: Bypass Protection Mechanism
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
