# CVE-2026-12064: proto-default skips SSH verification CVE-2026-12064 is fixed in 13 products on 1 platform, first by curl 8.18.0-1ubuntu2.3, released June 24, 2026. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2026-12064 - Priority: High - CVSS: 7.5 (Important) - EPSS: 0.0041 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Jun 24, 2026 - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-12064 ## Description When a user invokes curl using a schemeless URL combined with `--proto-default` sftp (or scp), a disconnect occurs between the tool layer and libcurl. The tool layer incorrectly infers the URL scheme, which erroneously bypasses the initialization of critical SSH security options like CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256 and CURLOPT_SSH_KNOWNHOSTS. Conversely, the libcurl runtime successfully honors CURLOPT_DEFAULT_PROTOCOL and establishes the connection via SFTP/SCP as specified. Because the tool layer skipped the security configuration, these SSH host verification options are silently omitted, causing curl to connect to an unverified SSH remote host without throwing an error. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | curl Debian 14 | 8.21.0~rc3-1 | [DEBIAN-CVE-2026-12064](https://patchblox.com/security/data/fix/linux/debian-cve-2026-12064.md) | Jul 24, 2026 | | Linux | curl RHEL 10 | 8.12.1-1.el10_0.10 | [RHSA-2026:72506](https://patchblox.com/security/data/fix/linux/rhsa-2026-72506.md) | Jul 3, 2026 | | Linux | curl Ubuntu 25.10 (questing) | 8.14.1-2ubuntu1.5 | [curl 8.14.1-2ubuntu1.5](https://patchblox.com/security/data/fix/linux/ubuntu-questing-curl-8.14.1-2ubuntu1.5.md) | Jul 21, 2026 | | Linux | curl Ubuntu 26.04.1 LTS (resolute) | 8.18.0-1ubuntu2.3 | [curl 8.18.0-1ubuntu2.3](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-curl-8.18.0-1ubuntu2.3.md) | Jun 24, 2026 | | Linux | curl amzn 2023 | 8.21.0-5.amzn2023.0.1 | [ALAS2023-2026-2132](https://patchblox.com/security/data/fix/linux/alas2023-2026-2132.md) | Sep 14, 2026 | | Linux | curl ol 10 | 0:8.12.1-4.el10_2.4 | [ELSA-2026-55450](https://patchblox.com/security/data/fix/linux/elsa-2026-55450.md) | Aug 17, 2026 | | Linux | curl opensuse-leap 16.0 | 8.14.1-160000.8.1 | [OPENSUSE-SU-2026:21272-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21272-1.md) | Jul 8, 2026 | | Linux | curl sles 15.6 | 8.22.0-150600.4.58.1 | [SUSE-SU-2026:5069-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5069-1.md) | Nov 7, 2026 | | Linux | curl sles 15.7 | 8.22.0-150700.7.33.1 | [SUSE-SU-2026:5068-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5068-1.md) | Nov 7, 2026 | | Linux | curl sles 16.0 | 8.14.1-160000.8.1 | [SUSE-SU-2026:22582-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22582-1.md) | Jul 8, 2026 | | Linux | curl-debuginfo amzn 2023 | 8.21.0-5.amzn2023.0.1 | [ALAS2023-2026-2132](https://patchblox.com/security/data/fix/linux/alas2023-2026-2132.md) | Sep 14, 2026 | | Linux | curl-debugsource amzn 2023 | 8.21.0-5.amzn2023.0.1 | [ALAS2023-2026-2132](https://patchblox.com/security/data/fix/linux/alas2023-2026-2132.md) | Sep 14, 2026 | | Linux | curl-mini sles 16.0 | 8.14.1-160000.8.1 | [SUSE-SU-2026:22582-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22582-1.md) | Jul 8, 2026 | | Linux | curl-minimal amzn 2023 | 8.21.0-5.amzn2023.0.1 | [ALAS2023-2026-2132](https://patchblox.com/security/data/fix/linux/alas2023-2026-2132.md) | Sep 14, 2026 | | Linux | curl-minimal-debuginfo amzn 2023 | 8.21.0-5.amzn2023.0.1 | [ALAS2023-2026-2132](https://patchblox.com/security/data/fix/linux/alas2023-2026-2132.md) | Sep 14, 2026 | | Linux | libcurl amzn 2023 | 8.21.0-5.amzn2023.0.1 | [ALAS2023-2026-2132](https://patchblox.com/security/data/fix/linux/alas2023-2026-2132.md) | Sep 14, 2026 | | Linux | libcurl ol 10 | 0:8.12.1-4.el10_2.4 | [ELSA-2026-55450](https://patchblox.com/security/data/fix/linux/elsa-2026-55450.md) | Aug 17, 2026 | | Linux | libcurl-debuginfo amzn 2023 | 8.21.0-5.amzn2023.0.1 | [ALAS2023-2026-2132](https://patchblox.com/security/data/fix/linux/alas2023-2026-2132.md) | Sep 14, 2026 | | Linux | libcurl-devel amzn 2023 | 8.21.0-5.amzn2023.0.1 | [ALAS2023-2026-2132](https://patchblox.com/security/data/fix/linux/alas2023-2026-2132.md) | Sep 14, 2026 | | Linux | libcurl-devel ol 10 | 0:8.12.1-4.el10_2.4 | [ELSA-2026-55450](https://patchblox.com/security/data/fix/linux/elsa-2026-55450.md) | Aug 17, 2026 | | Linux | libcurl-minimal amzn 2023 | 8.21.0-5.amzn2023.0.1 | [ALAS2023-2026-2132](https://patchblox.com/security/data/fix/linux/alas2023-2026-2132.md) | Sep 14, 2026 | | Linux | libcurl-minimal ol 10 | 0:8.12.1-4.el10_2.4 | [ELSA-2026-55450](https://patchblox.com/security/data/fix/linux/elsa-2026-55450.md) | Aug 17, 2026 | | Linux | libcurl-minimal-debuginfo amzn 2023 | 8.21.0-5.amzn2023.0.1 | [ALAS2023-2026-2132](https://patchblox.com/security/data/fix/linux/alas2023-2026-2132.md) | Sep 14, 2026 | | Linux | libcurl3t64-gnutls Ubuntu 25.10 (questing) | 8.14.1-2ubuntu1.5 | [libcurl3t64-gnutls 8.14.1-2ubuntu1.5](https://patchblox.com/security/data/fix/linux/ubuntu-questing-libcurl3t64-gnutls-8.14.1-2ubuntu1.5.md) | Jul 21, 2026 | | Linux | libcurl3t64-gnutls Ubuntu 26.04.1 LTS (resolute) | 8.18.0-1ubuntu2.3 | [libcurl3t64-gnutls 8.18.0-1ubuntu2.3](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libcurl3t64-gnutls-8.18.0-1ubuntu2.3.md) | Jun 24, 2026 | | Linux | libcurl4t64 Ubuntu 25.10 (questing) | 8.14.1-2ubuntu1.5 | [libcurl4t64 8.14.1-2ubuntu1.5](https://patchblox.com/security/data/fix/linux/ubuntu-questing-libcurl4t64-8.14.1-2ubuntu1.5.md) | Jul 21, 2026 | | Linux | libcurl4t64 Ubuntu 26.04.1 LTS (resolute) | 8.18.0-1ubuntu2.3 | [libcurl4t64 8.18.0-1ubuntu2.3](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libcurl4t64-8.18.0-1ubuntu2.3.md) | Jun 24, 2026 | --- Data as of 2026-11-09T07:25:28Z UTC. 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