# CVE-2026-5545: wrong reuse of HTTP Negotiate connection CVE-2026-5545 is fixed in 10 products on 1 platform, first by curl 7.68.0-1ubuntu2.25+esm5, released April 29, 2026. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2026-5545 - Priority: Routine - CVSS: 6.5 (Moderate) - EPSS: 0.0041 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Apr 29, 2026 - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-5545 ## Description libcurl might in some circumstances reuse the wrong connection when asked to do an authenticated HTTP(S) request after a Negotiate-authenticated one, when both use the same host. libcurl features a pool of recent connections so that subsequent requests can reuse an existing connection to avoid overhead. When reusing a connection a range of criteria must be met. Due to a logical error in the code, a request that was issued by an application could wrongfully reuse an existing connection to the same server that was authenticated using different credentials. An application that first uses Negotiate authentication to a server with `user1:password1` and then does another operation to the same server asking for any authentication method but for `user2:password2` (while the previous connection is still alive) - the second request gets confused and wrongly reuses the same connection and sends the new request over that connection thinking it uses a mix of user1's and user2's credentials when it is in fact still using the connection authenticated for user1... ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | curl Debian 13.5 (trixie) | 8.14.1-2+deb13u4 | [DEBIAN-CVE-2026-5545](https://patchblox.com/security/data/fix/linux/debian-cve-2026-5545.md) | May 15, 2026 | | Linux | curl Debian 14 | 8.20.0~rc2-1 | [DEBIAN-CVE-2026-5545](https://patchblox.com/security/data/fix/linux/debian-cve-2026-5545.md) | May 15, 2026 | | Linux | curl RHEL 10 | 8.12.1-4.el10_2.7 | [RHSA-2026:80512](https://patchblox.com/security/data/fix/linux/rhsa-2026-80512.md) | Jul 3, 2026 | | Linux | curl Ubuntu 20.04 LTS (focal) | 7.68.0-1ubuntu2.25+esm5 | [curl 7.68.0-1ubuntu2.25+esm5](https://patchblox.com/security/data/fix/linux/ubuntu-focal-curl-7.68.0-1ubuntu2.25-esm5.md) | Apr 29, 2026 | | Linux | curl Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.24 | [curl 7.81.0-1ubuntu1.24](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-curl-7.81.0-1ubuntu1.24.md) | May 15, 2026 | | Linux | curl Ubuntu 24.04.5 LTS (noble) | 8.5.0-2ubuntu10.9 | [curl 8.5.0-2ubuntu10.9](https://patchblox.com/security/data/fix/linux/ubuntu-noble-curl-8.5.0-2ubuntu10.9.md) | May 15, 2026 | | Linux | curl Ubuntu 25.10 (questing) | 8.14.1-2ubuntu1.3 | [curl 8.14.1-2ubuntu1.3](https://patchblox.com/security/data/fix/linux/ubuntu-questing-curl-8.14.1-2ubuntu1.3.md) | May 15, 2026 | | Linux | curl Ubuntu 26.04.1 LTS (resolute) | 8.18.0-1ubuntu2.1 | [curl 8.18.0-1ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-curl-8.18.0-1ubuntu2.1.md) | Apr 29, 2026 | | Linux | curl almalinux 10 | 8.12.1-4.el10_2.7 | [ALSA-2026:80512](https://patchblox.com/security/data/fix/linux/alsa-2026-80512.md) | Nov 7, 2026 | | Linux | curl ol 10 | 0:8.12.1-4.el10_2.7 | [ELSA-2026-80512](https://patchblox.com/security/data/fix/linux/elsa-2026-80512.md) | Nov 7, 2026 | | Linux | curl opensuse-leap 16.0 | 8.14.1-160000.6.1 | [OPENSUSE-SU-2026:20973-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20973-1.md) | Jun 17, 2026 | | Linux | curl rocky 10 | 0:8.12.1-4.el10_2.7 | [RLSA-2026:80512](https://patchblox.com/security/data/fix/linux/rlsa-2026-80512.md) | Nov 7, 2026 | | Linux | curl sles 15.7 | 8.14.1-150700.7.23.1 | [SUSE-SU-2026:3798-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-3798-1.md) | Aug 25, 2026 | | Linux | curl sles 16.0 | 8.14.1-160000.6.1 | [SUSE-SU-2026:22156-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22156-1.md) | Jun 17, 2026 | | Linux | curl-mini sles 16.0 | 8.14.1-160000.6.1 | [SUSE-SU-2026:22156-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22156-1.md) | Jun 17, 2026 | | Linux | libcurl almalinux 10 | 8.12.1-4.el10_2.7 | [ALSA-2026:80512](https://patchblox.com/security/data/fix/linux/alsa-2026-80512.md) | Nov 7, 2026 | | Linux | libcurl ol 10 | 0:8.12.1-4.el10_2.7 | [ELSA-2026-80512](https://patchblox.com/security/data/fix/linux/elsa-2026-80512.md) | Nov 7, 2026 | | Linux | libcurl-devel almalinux 10 | 8.12.1-4.el10_2.7 | [ALSA-2026:80512](https://patchblox.com/security/data/fix/linux/alsa-2026-80512.md) | Nov 7, 2026 | | Linux | libcurl-devel ol 10 | 0:8.12.1-4.el10_2.7 | [ELSA-2026-80512](https://patchblox.com/security/data/fix/linux/elsa-2026-80512.md) | Nov 7, 2026 | | Linux | libcurl-minimal almalinux 10 | 8.12.1-4.el10_2.7 | [ALSA-2026:80512](https://patchblox.com/security/data/fix/linux/alsa-2026-80512.md) | Nov 7, 2026 | | Linux | libcurl-minimal ol 10 | 0:8.12.1-4.el10_2.7 | [ELSA-2026-80512](https://patchblox.com/security/data/fix/linux/elsa-2026-80512.md) | Nov 7, 2026 | | Linux | libcurl3-gnutls Ubuntu 20.04 LTS (focal) | 7.68.0-1ubuntu2.25+esm5 | [libcurl3-gnutls 7.68.0-1ubuntu2.25+esm5](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libcurl3-gnutls-7.68.0-1ubuntu2.25-esm5.md) | Apr 29, 2026 | | Linux | libcurl3-gnutls Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.24 | [libcurl3-gnutls 7.81.0-1ubuntu1.24](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libcurl3-gnutls-7.81.0-1ubuntu1.24.md) | May 15, 2026 | | Linux | libcurl3-nss Ubuntu 20.04 LTS (focal) | 7.68.0-1ubuntu2.25+esm5 | [libcurl3-nss 7.68.0-1ubuntu2.25+esm5](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libcurl3-nss-7.68.0-1ubuntu2.25-esm5.md) | Apr 29, 2026 | | Linux | libcurl3-nss Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.24 | [libcurl3-nss 7.81.0-1ubuntu1.24](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libcurl3-nss-7.81.0-1ubuntu1.24.md) | May 15, 2026 | | Linux | libcurl3t64-gnutls Ubuntu 24.04.5 LTS (noble) | 8.5.0-2ubuntu10.9 | [libcurl3t64-gnutls 8.5.0-2ubuntu10.9](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libcurl3t64-gnutls-8.5.0-2ubuntu10.9.md) | May 15, 2026 | | Linux | libcurl3t64-gnutls Ubuntu 25.10 (questing) | 8.14.1-2ubuntu1.3 | [libcurl3t64-gnutls 8.14.1-2ubuntu1.3](https://patchblox.com/security/data/fix/linux/ubuntu-questing-libcurl3t64-gnutls-8.14.1-2ubuntu1.3.md) | May 15, 2026 | | Linux | libcurl3t64-gnutls Ubuntu 26.04.1 LTS (resolute) | 8.18.0-1ubuntu2.1 | [libcurl3t64-gnutls 8.18.0-1ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libcurl3t64-gnutls-8.18.0-1ubuntu2.1.md) | Apr 29, 2026 | | Linux | libcurl4 Ubuntu 20.04 LTS (focal) | 7.68.0-1ubuntu2.25+esm5 | [libcurl4 7.68.0-1ubuntu2.25+esm5](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libcurl4-7.68.0-1ubuntu2.25-esm5.md) | Apr 29, 2026 | | Linux | libcurl4 Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.24 | [libcurl4 7.81.0-1ubuntu1.24](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libcurl4-7.81.0-1ubuntu1.24.md) | May 15, 2026 | | Linux | libcurl4t64 Ubuntu 24.04.5 LTS (noble) | 8.5.0-2ubuntu10.9 | [libcurl4t64 8.5.0-2ubuntu10.9](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libcurl4t64-8.5.0-2ubuntu10.9.md) | May 15, 2026 | | Linux | libcurl4t64 Ubuntu 25.10 (questing) | 8.14.1-2ubuntu1.3 | [libcurl4t64 8.14.1-2ubuntu1.3](https://patchblox.com/security/data/fix/linux/ubuntu-questing-libcurl4t64-8.14.1-2ubuntu1.3.md) | May 15, 2026 | | Linux | libcurl4t64 Ubuntu 26.04.1 LTS (resolute) | 8.18.0-1ubuntu2.1 | [libcurl4t64 8.18.0-1ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libcurl4t64-8.18.0-1ubuntu2.1.md) | Apr 29, 2026 | --- Data as of 2026-11-08T00:53:09Z UTC. 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