CVE-2026-6253

Published: May 13, 2026Modified: Jun 17, 2026

5.9

Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitability: 2.2 / Impact: 3.6

Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0 (Secondary)

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

Affected (1)

Products: Haxx: Curl

1 product

Configuration A

1 vulnerable

Vulnerable Software	Affected Versions
Haxx Curl	From 7.14.1 to 8.20.0

Related CWEs

Insufficiently Protected Credentials

The product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval.

References (5)

https://curl.se/docs/CVE-2026-6253.html

Source: 2499f714-1537-4658-8207-48ae4bb9eae9

PatchVendor 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

ExploitIssue TrackingThird Party Advisory

http://www.openwall.com/lists/oss-security/2026/04/29/11

Source: af854a3a-2127-422b-91ae-364da2661108

Mailing ListPatchThird Party Advisory

https://hackerone.com/reports/3669637

Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0

ExploitIssue TrackingThird Party Advisory

Timeline

No history available yet.