CVE-2026-6253
Published: May 1, 2026Last modified: May 5, 2026
Description
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
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 5.9 |
| Attack Vector | NETWORK |
| Attack complexity | HIGH |
| Privileges required | NONE |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | NONE |
| Integrity impact | NONE |
| Availability impact | HIGH |
| Vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H |
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | curl | Fixed (8.20.0-r0) |
| 25 LTS | curl | Fixed (8.20.0-r0) | |
| Stream | curl | Fixed (8.20.0-r0) | |
| Hardened Containers | Stream | curl | Fixed (8.20.0-r0) |