| Name | CVE-2026-6253 |
| 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 |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| curl (PTS) | bullseye | 7.74.0-1.3+deb11u13 | vulnerable |
| bullseye (security) | 7.74.0-1.3+deb11u16 | vulnerable | |
| bookworm | 7.88.1-10+deb12u14 | vulnerable | |
| bookworm (security) | 7.88.1-10+deb12u5 | vulnerable | |
| trixie | 8.14.1-2+deb13u3 | vulnerable | |
| forky | 8.20.0-1 | fixed | |
| sid | 8.20.0-2 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| curl | source | (unstable) | 8.20.0~rc3-1 |
[trixie] - curl <no-dsa> (Minor issue)
[bookworm] - curl <no-dsa> (Minor issue)
[bullseye] - curl <postponed> (Minor issue; can be fixed in next update)
https://curl.se/docs/CVE-2026-6253.html
Introduced by: https://github.com/curl/curl/commit/3b60bb725913ce7339aefef0a14b12df4c24db60 (curl-7_14_1)
Fixed by: https://github.com/curl/curl/commit/188c2f166a20fa97c2325b2da7d0e5cecc13725f (rc-8_20_0-3)