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

Affected products

Linuxmint, Red Os, Ubuntu, Curl

Haxx Curl

< 8.20.0

CVSS 3.1

5.9 MEDIUM

EPSS

0.7% (50th percentile)

Weakness

CWE-522

NVD status

Analyzed

Published

2026-05-13

No exploit for CVE-2026-6253 has been indexed yet. Our index is built from live traffic and upstream syncs, so this page can only say what it knows — not that no exploit exists.