Vulnerability · Published Jul 3, 2026 · Assigned by curl
CVE-2026-11856cross-origin Digest auth state leak
Critical 9.8
In plain English
A critical-severity security flaw in curl from curl. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 53% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)9.8Critical
Exploit odds (30 days)0.7%top 47.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official description
Successfully using libcurl to do a transfer to a specific HTTP origin (`hostA`) with **Digest** authentication and then changing the origin to a different one (`hostB`) for a second transfer, reusing the same handle, makes libcurl wrongly pass on the `Authorization:` header field meant for `hostA`, to `hostB`.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | curl | 8.12.1-4.el10_2.6 | ALSA-2026:69125 |
| AlmaLinux:8 | curl | 7.61.1-34.el8_10.18 | ALSA-2026:92368 |
| AlmaLinux:9 | curl | 7.76.1-40.el9_8.8 | ALSA-2026:80511 |
| AlmaLinux:9 | curl-minimal | 7.76.1-40.el9_8.8 | ALSA-2026:80511 |
| AlmaLinux:10 | libcurl | 8.12.1-4.el10_2.6 | ALSA-2026:69125 |
| AlmaLinux:8 | libcurl | 7.61.1-34.el8_10.18 | ALSA-2026:92368 |
| AlmaLinux:9 | libcurl | 7.76.1-40.el9_8.8 | ALSA-2026:80511 |
| AlmaLinux:10 | libcurl-devel | 8.12.1-4.el10_2.6 | ALSA-2026:69125 |
| AlmaLinux:8 | libcurl-devel | 7.61.1-34.el8_10.18 | ALSA-2026:92368 |
| AlmaLinux:9 | libcurl-devel | 7.76.1-40.el9_8.8 | ALSA-2026:80511 |
| AlmaLinux:10 | libcurl-minimal | 8.12.1-4.el10_2.6 | ALSA-2026:69125 |
| AlmaLinux:8 | libcurl-minimal | 7.61.1-34.el8_10.18 | ALSA-2026:92368 |
| AlmaLinux:9 | libcurl-minimal | 7.76.1-40.el9_8.8 | ALSA-2026:80511 |
| Alpine:v3.23 | curl | 8.22.0-r0 | ALPINE-CVE-2026-11856 |
| Alpine:v3.24 | curl | 8.21.0-r0 | ALPINE-CVE-2026-11856 |
| Debian:12 | curl | no fix listed | DEBIAN-CVE-2026-11856 |
| Debian:13 | curl | no fix listed | DEBIAN-CVE-2026-11856 |
| Debian:14 | curl | 8.21.0~rc3-1 | DEBIAN-CVE-2026-11856 |
| Rocky Linux:10 | curl | 0:8.12.1-4.el10_2.6 | RLSA-2026:69125 |
| Rocky Linux:8 | curl | 0:7.61.1-34.el8_10.18 | RLSA-2026:92368 |
| Rocky Linux:9 | curl | 0:7.76.1-40.el9_8.8 | RLSA-2026:80511 |
| Ubuntu:22.04:LTS | curl | 7.81.0-1ubuntu1.26 | UBUNTU-CVE-2026-11856 |
| Ubuntu:24.04:LTS | curl | 8.5.0-2ubuntu10.12 | UBUNTU-CVE-2026-11856 |
| Ubuntu:25.10 | curl | no fix listed | UBUNTU-CVE-2026-11856 |
| Ubuntu:26.04:LTS | curl | 8.18.0-1ubuntu2.4 | UBUNTU-CVE-2026-11856 |
Affected products (as reported)
Weakness: CWE-294 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H