stale custom cookie host causes cookie leak
CVE-2026-6276 is fixed in 7 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: High.
Using libcurl, when a custom `Host:` header is first set for an HTTP request and a second request is subsequently done using the same *easy handle* but without the custom `Host:` header set, the second request would use stale information and pass on cookies meant for the first host in the second request. Leak them.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| curl · Debian 13.5 (trixie) | 8.14.1-2+deb13u4 | DEBIAN-CVE-2026-6276 | May 15, 2026 |
| curl · Debian 14 | 8.20.0~rc3-1 | DEBIAN-CVE-2026-6276 | May 15, 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 · opensuse-leap 16.0 | 8.14.1-160000.6.1 | OPENSUSE-SU-2026:20973-1 | Jun 17, 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 |
| 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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