By default, curl automatically responds to WebSocket PING frames. Because curl lacks an upper bound on memory allocation for unacknowledged frames, a malicious server can exhaust all available memory by flooding curl with rapid, sequential PING messages.

A flaw was found in curl. A malicious server can exploit this vulnerability by sending rapid, sequential WebSocket PING messages. Due to a lack of an upper bound on memory allocation for unacknowledged frames, curl can be forced to exhaust all available memory, leading to a denial of service.

This Important denial of service vulnerability in curl allows a remote malicious server to exhaust system memory. By default, curl automatically responds to WebSocket PING frames without an upper bound on memory allocation, enabling an attacker to trigger resource exhaustion and cause service unavailability in affected Red Hat products. Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability. Red Hat Hardened Images 2026-06-24T00:00:00Z RHSA-2026:29017 curl-main-8.21.0-0.1.hum1 Red Hat Hardened Images 2026-07-02T00:00:00Z RHSA-2026:34975 rust-main-1.96.1-1.hum1 Red Hat Enterprise Linux 10 Affected curl Red Hat Enterprise Linux 6 Out of support scope curl Red Hat Enterprise Linux 7 Out of support scope curl Red Hat Enterprise Linux 8 Affected curl Red Hat Enterprise Linux 9 Affected curl Red Hat OpenShift Container Platform 4 Affected rhcos Red Hat OpenShift Dev Spaces Affected devspaces/code-rhel9 Red Hat Trusted Profile Analyzer Affected rhtpa/rhtpa-trustification-service-rhel9 https://www.cve.org/CVERecord?id=CVE-2026-11586 https://nvd.nist.gov/vuln/detail/CVE-2026-11586 https://curl.se/docs/CVE-2026-11586.html https://curl.se/docs/CVE-2026-11586.json https://hackerone.com/reports/3788931