CVE-2026-71190

In OpenStack Swift through 2.38.0, the proxy server Accept header parser contains a regular expression vulnerable to catastrophic backtracking (ReDoS). The "qdtext" pattern (?:[^"]|\\.)* allows an unauthenticated remote attacker to send a crafted Accept header that causes exponential CPU consumption in the proxy worker. A payload of 32 backslash-character pairs exceeds 30 seconds of CPU time. No authentication is required. Repeated requests can exhaust all proxy worker threads, resulting in a complete denial of service.

• https://launchpad.net/bugs/2158771
• https://openwall.com/lists/oss-security/2026/07/28/27
• https://security.openstack.org/ossa/OSSA-2026-031.html
• http://www.openwall.com/lists/oss-security/2026/08/05/19