Information disclosure in cURL - CVE-2026-9545

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Main Vulnerability Database Vulnerabilities #VU135087

Information disclosure in cURL - CVE-2026-9545

Published: June 24, 2026


Vulnerability identifier: #VU135087
CSH Severity: Low
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-9545
CWE-ID: CWE-200
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to disclose sensitive information.

The vulnerability exists due to exposure of sensitive information in libcurl HTTP/3 handling when reusing a cached SSL session with early data enabled after the original server is replaced by an impostor machine. A remote attacker can replace the server with an impostor machine and cause libcurl to send request bytes before certificate verification failure is enforced to disclose sensitive information.

This issue is specific to HTTP/3 with the ngtcp2 + nghttp3 backend and requires SSL session caching to remain enabled and TLS early data to be enabled.


Affected software

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

How to mitigate CVE-2026-9545

Install security update from vendor's website.

cURL - update to 8.21.0
LANTIME Operating System Firmware (LTOS) - update to 7.10.013
curl (Ubuntu package) - addressed in versions 7.35.0-1ubuntu2.20+esm20, 7.35.0-1ubuntu2.20+esm23, 7.47.0-1ubuntu2.19+esm16, 7.58.0-2ubuntu3.24+esm9, 7.68.0-1ubuntu2.25+esm4, 7.81.0-1ubuntu1.25, 8.5.0-2ubuntu10.10, 8.14.1-2ubuntu1.4, 8.18.0-1ubuntu2.2
curl - addressed in versions 7.71.1-52, 7.79.1-53, 8.4.0-35
curl-debuginfo - addressed in versions 7.71.1-52, 7.79.1-53, 8.4.0-35
curl-help - addressed in versions 7.71.1-52, 7.79.1-53, 8.4.0-35
libcurl-devel - addressed in versions 7.71.1-52, 7.79.1-53, 8.4.0-35
libcurl - addressed in versions 7.71.1-52, 7.79.1-53, 8.4.0-35
curl-debugsource - addressed in versions 7.71.1-52, 7.79.1-53, 8.4.0-35
libcurl-devel-64bit - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1
libcurl4-debuginfo - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1, 8.14.1-150700.7.20.1
libcurl4-32bit-debuginfo - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1, 8.14.1-150700.7.20.1
libcurl4-32bit - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1, 8.14.1-150700.7.20.1
libcurl4 - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1, 8.14.1-150700.7.20.1
curl-debuginfo - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1, 8.14.1-150700.7.20.1
libcurl-devel - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1, 8.14.1-150700.7.20.1
libcurl4-64bit-debuginfo - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1
libcurl4-64bit - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1
curl-fish-completion - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1
libcurl-devel-doc - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1
curl-zsh-completion - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1
libcurl-devel-32bit - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1
libcurl-mini4-debuginfo - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1
libcurl-mini4 - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1
curl-mini-debugsource - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1
curl - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1, 8.14.1-150700.7.20.1
curl-debugsource - addressed in versions 8.14.1-150400.5.86.1, 8.14.1-150600.4.46.1, 8.14.1-150700.7.20.1
curl - addressed in versions 8.15.0-9.fc43, 8.18.0-9.fc44

External References

Related Security Bulletins