Authentication Bypass by Primary Weakness in cURL - CVE-2026-5545

Vulnerability identifier: #VU128460

CSH Severity: Medium

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

CVE-ID: CVE-2026-5545

CWE-ID: CWE-305

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to compromise the target system.

The vulnerability exists due to wrong reuse of HTTP Negotiate authentication connection. A remote attacker can execute arbitrary requests under the wrong user context.

cURL
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server 12 SP5 LTSS Extended
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server for SAP Applications 12
SUSE Linux Enterprise Real Time 15
SUSE Manager Proxy
SUSE Manager Server
SUSE Manager Retail Branch Server
SUSE Linux Enterprise Micro
SUSE Linux Enterprise Micro for Rancher
Ubuntu
Basesystem Module
openSUSE Leap
openEuler
Anolis OS
LANTIME Operating System Firmware (LTOS)
curl (Ubuntu package)
curl
curl-debuginfo
curl-debugsource
libcurl
libcurl-devel
curl-help
libcurl4
libcurl4-debuginfo-32bit
libcurl4-32bit
libcurl4-debuginfo
curl-doc
libcurl-minimal
curl-minimal
libcurl-mini4-debuginfo
libcurl-devel-64bit
libcurl4-64bit-debuginfo
libcurl4-64bit
libcurl-devel-32bit
libcurl-devel-doc
curl-fish-completion
curl-zsh-completion
libcurl-mini4
curl-mini-debugsource
libcurl4-32bit-debuginfo

Install updates from vendor's website.

cURL - update to 8.20.0
LANTIME Operating System Firmware (LTOS) - update to 7.10.012
curl (Ubuntu package) - addressed in versions 7.35.0-1ubuntu2.20+esm21, 7.47.0-1ubuntu2.19+esm17, 7.58.0-2ubuntu3.24+esm10, 7.68.0-1ubuntu2.25+esm5, 7.81.0-1ubuntu1.24, 8.5.0-2ubuntu10.9, 8.5.0-2ubuntu10.11, 8.14.1-2ubuntu1.3, 8.14.1-2ubuntu1.5, 8.18.0-1ubuntu2.1, 8.18.0-1ubuntu2.3
curl - addressed in versions 7.71.1-48, 7.79.1-49, 8.4.0-29, 8.4.0-30
curl-debuginfo - addressed in versions 7.71.1-48, 7.79.1-49, 8.4.0-29, 8.4.0-30
curl-debugsource - addressed in versions 7.71.1-48, 7.79.1-49, 8.4.0-29, 8.4.0-30
libcurl - addressed in versions 7.71.1-48, 7.79.1-49, 8.4.0-29, 8.4.0-30
libcurl-devel - addressed in versions 7.71.1-48, 7.79.1-49, 8.4.0-29, 8.4.0-30
curl-help - addressed in versions 7.71.1-48, 7.79.1-49, 8.4.0-29, 8.4.0-30
curl-debugsource - addressed in versions 8.0.1-11.123.1, 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1, 8.14.1-150700.7.23.1
libcurl4 - addressed in versions 8.0.1-11.123.1, 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1, 8.14.1-150700.7.23.1
libcurl4-debuginfo-32bit - update to 8.0.1-11.123.1
libcurl4-32bit - addressed in versions 8.0.1-11.123.1, 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1, 8.14.1-150700.7.23.1
curl-debuginfo - addressed in versions 8.0.1-11.123.1, 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1, 8.14.1-150700.7.23.1
curl - addressed in versions 8.0.1-11.123.1, 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1, 8.14.1-150700.7.23.1
libcurl4-debuginfo - addressed in versions 8.0.1-11.123.1, 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1, 8.14.1-150700.7.23.1
libcurl-devel - addressed in versions 8.0.1-11.123.1, 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1, 8.14.1-150700.7.23.1
curl-doc - update to 8.4.0-24
libcurl-devel - update to 8.4.0-24
libcurl-minimal - update to 8.4.0-24
curl - update to 8.4.0-24
libcurl - update to 8.4.0-24
curl-minimal - update to 8.4.0-24
libcurl-mini4-debuginfo - addressed in versions 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1
libcurl-devel-64bit - addressed in versions 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1
libcurl4-64bit-debuginfo - addressed in versions 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1
libcurl4-64bit - addressed in versions 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1
libcurl-devel-32bit - addressed in versions 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1
libcurl-devel-doc - addressed in versions 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1
curl-fish-completion - addressed in versions 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1
curl-zsh-completion - addressed in versions 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1
libcurl-mini4 - addressed in versions 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1
curl-mini-debugsource - addressed in versions 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1
libcurl4-32bit-debuginfo - addressed in versions 8.14.1-150400.5.83.1, 8.14.1-150600.4.43.1, 8.14.1-150700.7.23.1

• https://curl.se/docs/CVE-2026-5545.html

• Multiple vulnerabilities in curl
• Ubuntu update for curl
• SUSE update for curl
• SUSE update for curl
• openEuler 20.03 LTS SP4 update for curl
• openEuler 24.03 LTS SP3 update for curl
• openEuler 24.03 LTS update for curl
• openEuler 22.03 LTS SP4 update for curl
• openEuler 24.03 LTS SP1 update for curl
• SUSE update for curl
• Ubuntu update for curl
• Anolis OS update for curl
• Multiple vulnerabilities in Meinberg LANTIME Operating System Firmware
• SUSE update for curl