CVE-2026-6253

5.9 MEDIUM
Published: May 13, 2026 Modified: May 14, 2026
View on NVD

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

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://curl.se/docs/CVE-2026-6253.html
Source: 2499f714-1537-4658-8207-48ae4bb9eae9
Patch Vendor Advisory
https://curl.se/docs/CVE-2026-6253.json
Source: 2499f714-1537-4658-8207-48ae4bb9eae9
Vendor Advisory
https://hackerone.com/reports/3669637
Source: 2499f714-1537-4658-8207-48ae4bb9eae9
Exploit Issue Tracking Third Party Advisory
http://www.openwall.com/lists/oss-security/2026/04/29/11
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List Patch Third Party Advisory
https://hackerone.com/reports/3669637
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Exploit Issue Tracking Third Party Advisory

5 reference(s) from NVD

Quick Stats

CVSS v3 Score
5.9 / 10.0
EPSS (Exploit Probability)
0.5%
40th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

haxx