CVE-2026-86463: Apache CXF: FIQL Query Parser Denial of Service
Apache CXF's FIQL query parser has a vulnerability in how it searches for operators in query expressions. The search pattern can get stuck trying many combinations when it encounters a long string without an operator, causing the parser to consume excessive CPU time. An attacker can send a crafted query to make the server use up CPU resources, potentially slowing down or stopping other requests. The fix was to limit FIQL expressions to 4 KiB by default, preventing attackers from sending extremely long inputs while still allowing normal queries.
Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Apache CXFto a version that resolves this vulnerability.Fixed in 4.2.4
Event History
Frequently Asked Questions
What does an attacker need to exploit this issue?
An attacker needs to be able to send a crafted FIQL query expression to a CXF endpoint that parses FIQL queries. The malicious input is a long expression without an operator, which causes excessive CPU consumption during operator searching.
Are normal FIQL queries likely to be disrupted by the fix?
The fix limits FIQL expressions to 4 KiB by default. This is intended to block extremely long malicious inputs while continuing to allow normal queries.
Which versions contain the fix?
Upgrade to Apache CXF 4.2.4, 4.1.9, or 3.6.13. These versions include the FIQL expression length limit.