CVE-2026-6253
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
- Published May 13, 2026
- CVSS 5.9 medium
- 0.8% chance of exploitation in the next 30 days (EPSS)
- Public exploit code is available
- A fix is available
Affected software
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