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Ubuntu 20.04 curl Critical Authentication Issues USN-8099-1 CVE-2026-1965

Several security issues were fixed in curl.. ========================================================================== Ubuntu Security Notice USN-8099-1 March 16, 2026 curl vulnerabilities ========================================================================== A security issue affects these releases of Ubuntu and its derivatives: - Ubuntu 20.04 LTS - Ubuntu 18.04 LTS Summary: Several security issues were fixed in curl. Software Description: - curl: HTTP, HTTPS, and FTP client and client libraries Details: Zhicheng Chen discovered that curl could incorrectly reuse the wrong connection for Negotiate-authenticated HTTP or HTTPS requests. This could result in the use of credentials from a different connection, contrary to expectations. This issue only affected Ubuntu 20.04 LTS. (CVE-2026-1965) It was discovered that curl incorrectly leaked OAuth2 bearer tokens when following a redirect. This could result in tokens being sent to the wrong host, contrary to expectations. This issue only affected Ubuntu 20.04 LTS. (CVE-2026-3783) Muhamad Arga Reksapati discovered that curl incorrectly reused existing HTTP proxy connections even if the request used different credentials. This could result in the use of incorrect credentials, contrary to expectations. (CVE-2026-3784) Update instructions: The problem can be corrected by updating your system to the following package versions: Ubuntu 20.04 LTS curl 7.68.0-1ubuntu2.25+esm3 Available with Ubuntu Pro libcurl3-gnutls 7.68.0-1ubuntu2.25+esm3 Available with Ubuntu Pro libcurl3-nss 7.68.0-1ubuntu2.25+esm3 Available with Ubuntu Pro libcurl4 7.68.0-1ubuntu2.25+esm3 Available with Ubuntu Pro Ubuntu 18.04 LTS curl 7.58.0-2ubuntu3.24+esm8 Available with Ubuntu Pro libcurl3-gnutls 7.58.0-2ubuntu3.24+esm8 Available with Ubuntu Pro libcurl3-nss 7.58.0-2ubuntu3.24+esm8 Available with Ubuntu Pro libcurl4 7.58.0-2ubuntu3.24+esm8 Available with Ubuntu Pro In general, a standard system update will make all the necessary changes. References: https://ubuntu.com/security/notices/USN-8099-1 CVE-2026-1965, CVE-2026-3783, CVE-2026-3784 . Several critical security issues fixed in curl for Ubuntu 20.04 and 18.04 that could lead to credential leaks and unauthorized access.. curl security, Ubuntu curl vulnerabilities, HTTP client security issues, authentication flaws, security updates. . Severity: Critical. LinuxSecurity.com Team

Mar 16, 2026 •Critical Ubuntu