proxy credentials leak over redirect-to proxy
CVE-2026-6253 is fixed in 10 products on 1 platform, first by curl 8.18.0-1ubuntu2.1, released April 29, 2026. It is not reported as exploited. Patch Radar priority: Routine.
curl might erroneously pass on credentials for a first proxy to a second proxy. This can happen when the following conditions are true: 1. curl is setup to use specific different proxies for different URL schemes 2. the first proxy needs credentials 3. the second proxy uses no credentials 4. while using the first proxy (using say `http://`), curl is asked to follow a redirect to a URL using another scheme (say `https://`), accessed using a second, different, proxy
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| curl · Debian 13.5 (trixie) | 8.14.1-2+deb13u4 | DEBIAN-CVE-2026-6253 | May 15, 2026 |
| curl · Debian 14 | 8.20.0~rc3-1 | DEBIAN-CVE-2026-6253 | May 15, 2026 |
| curl · RHEL 10 | 8.12.1-4.el10_2.7 | RHSA-2026:80512 | Jul 3, 2026 |
| curl · Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.24 | curl 7.81.0-1ubuntu1.24 | May 15, 2026 |
| curl · Ubuntu 24.04.5 LTS (noble) | 8.5.0-2ubuntu10.9 | curl 8.5.0-2ubuntu10.9 | May 15, 2026 |
| curl · Ubuntu 25.10 (questing) | 8.14.1-2ubuntu1.3 | curl 8.14.1-2ubuntu1.3 | May 15, 2026 |
| curl · Ubuntu 26.04.1 LTS (resolute) | 8.18.0-1ubuntu2.1 | curl 8.18.0-1ubuntu2.1 | Apr 29, 2026 |
| curl · almalinux 10 | 8.12.1-4.el10_2.7 | ALSA-2026:80512 | Nov 7, 2026 |
| curl · ol 10 | 0:8.12.1-4.el10_2.7 | ELSA-2026-80512 | Nov 7, 2026 |
| curl · opensuse-leap 16.0 | 8.14.1-160000.6.1 | OPENSUSE-SU-2026:20973-1 | Jun 17, 2026 |
| curl · rocky 10 | 0:8.12.1-4.el10_2.7 | RLSA-2026:80512 | Nov 7, 2026 |
| curl · sles 15.7 | 8.14.1-150700.7.23.1 | SUSE-SU-2026:3798-1 | Aug 25, 2026 |
| curl · sles 16.0 | 8.14.1-160000.6.1 | SUSE-SU-2026:22156-1 | Jun 17, 2026 |
| curl-mini · sles 16.0 | 8.14.1-160000.6.1 | SUSE-SU-2026:22156-1 | Jun 17, 2026 |
| libcurl · almalinux 10 | 8.12.1-4.el10_2.7 | ALSA-2026:80512 | Nov 7, 2026 |
| libcurl · ol 10 | 0:8.12.1-4.el10_2.7 | ELSA-2026-80512 | Nov 7, 2026 |
| libcurl-devel · almalinux 10 | 8.12.1-4.el10_2.7 | ALSA-2026:80512 | Nov 7, 2026 |
| libcurl-devel · ol 10 | 0:8.12.1-4.el10_2.7 | ELSA-2026-80512 | Nov 7, 2026 |
| libcurl-minimal · almalinux 10 | 8.12.1-4.el10_2.7 | ALSA-2026:80512 | Nov 7, 2026 |
| libcurl-minimal · ol 10 | 0:8.12.1-4.el10_2.7 | ELSA-2026-80512 | Nov 7, 2026 |
| libcurl3-gnutls · Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.24 | libcurl3-gnutls 7.81.0-1ubuntu1.24 | May 15, 2026 |
| libcurl3-nss · Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.24 | libcurl3-nss 7.81.0-1ubuntu1.24 | May 15, 2026 |
| libcurl3t64-gnutls · Ubuntu 24.04.5 LTS (noble) | 8.5.0-2ubuntu10.9 | libcurl3t64-gnutls 8.5.0-2ubuntu10.9 | May 15, 2026 |
| libcurl3t64-gnutls · Ubuntu 25.10 (questing) | 8.14.1-2ubuntu1.3 | libcurl3t64-gnutls 8.14.1-2ubuntu1.3 | May 15, 2026 |
| libcurl3t64-gnutls · Ubuntu 26.04.1 LTS (resolute) | 8.18.0-1ubuntu2.1 | libcurl3t64-gnutls 8.18.0-1ubuntu2.1 | Apr 29, 2026 |
| libcurl4 · Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.24 | libcurl4 7.81.0-1ubuntu1.24 | May 15, 2026 |
| libcurl4t64 · Ubuntu 24.04.5 LTS (noble) | 8.5.0-2ubuntu10.9 | libcurl4t64 8.5.0-2ubuntu10.9 | May 15, 2026 |
| libcurl4t64 · Ubuntu 25.10 (questing) | 8.14.1-2ubuntu1.3 | libcurl4t64 8.14.1-2ubuntu1.3 | May 15, 2026 |
| libcurl4t64 · Ubuntu 26.04.1 LTS (resolute) | 8.18.0-1ubuntu2.1 | libcurl4t64 8.18.0-1ubuntu2.1 | Apr 29, 2026 |
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