Use-after-free in cURL - CVE-2026-18924

Vulnerability identifier: #VU146684

CSH Severity: Low

CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-18924

CWE-ID: CWE-416

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to trigger a use-after-free.

The vulnerability exists due to use-after-free in libcurl HTTP/2 server push stream handling when processing an HTTPS HTTP/2 server push on a shared connection. A remote attacker can send a server push response sequence to trigger a use-after-free.

The issue affects libcurl only and requires HTTP/2 server push to be enabled and accepted by the application, along with connection sharing.

cURL
Ubuntu
openEuler
Anolis OS
Fedora
curl-help
libcurl-devel
libcurl
curl-debugsource
curl-debuginfo
curl
curl-minimal
libcurl-minimal
curl-doc
curl (Ubuntu package)

Install security update from vendor's website.

cURL - update to 8.22.0
curl-help - addressed in versions 7.71.1-54, 7.79.1-56, 8.4.0-37
libcurl-devel - addressed in versions 7.71.1-54, 7.79.1-56, 8.4.0-37
libcurl - addressed in versions 7.71.1-54, 7.79.1-56, 8.4.0-37
curl-debugsource - addressed in versions 7.71.1-54, 7.79.1-56, 8.4.0-37
curl-debuginfo - addressed in versions 7.71.1-54, 7.79.1-56, 8.4.0-37
curl - addressed in versions 7.71.1-54, 7.79.1-56, 8.4.0-37
curl - update to 8.4.0-30
curl-minimal - update to 8.4.0-30
libcurl - update to 8.4.0-30
libcurl-devel - update to 8.4.0-30
libcurl-minimal - update to 8.4.0-30
curl-doc - update to 8.4.0-30
curl - addressed in versions 8.18.0-11.fc44, 8.18.0-12.fc44, 8.21.0-6.fc45
curl (Ubuntu package) - addressed in versions 7.47.0-1ubuntu2.19+esm20, 7.58.0-2ubuntu3.24+esm14, 7.68.0-1ubuntu2.25+esm9, 7.81.0-1ubuntu1.29, 8.5.0-2ubuntu10.15, 8.18.0-1ubuntu2.7

• https://curl.se/docs/CVE-2026-18924.html
• https://github.com/curl/curl/commit/90325ff0444cbdff368bda5d26d6

• Multiple vulnerabilities in cURL
• openEuler 24.03 LTS SP4 update for curl
• openEuler 24.03 LTS SP3 update for curl
• openEuler 24.03 LTS SP1 update for curl
• openEuler 22.03 LTS SP4 update for curl
• openEuler 20.03 LTS SP4 update for curl
• Ubuntu update for curl
• Fedora 45 update for curl
• Fedora 44 update for curl
• Fedora 44 update for curl
• Anolis OS update for curl