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
Metrics
Affected Vendors & Products
| Vendors | Products |
|---|---|
| Curl |
|
No data.
No data.
References
History
Wed, 13 May 2026 09:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | A flaw was found in curl. When curl is configured to use distinct proxies for different URL schemes, a redirect from a URL using an authenticated proxy to one using an unauthenticated proxy can inadvertently expose the initial proxy's credentials. This improper credential management (CWE-522) may allow an attacker to gain unauthorized access or information by intercepting these disclosed credentials. | 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 |
| Title | curl: curl: Proxy credential disclosure via redirects to unauthenticated proxies | proxy credentials leak over redirect-to proxy |
| References |
|
Fri, 01 May 2026 01:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Curl
Curl curl |
|
| Vendors & Products |
Curl
Curl curl |
Fri, 01 May 2026 00:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | A flaw was found in curl. When curl is configured to use distinct proxies for different URL schemes, a redirect from a URL using an authenticated proxy to one using an unauthenticated proxy can inadvertently expose the initial proxy's credentials. This improper credential management (CWE-522) may allow an attacker to gain unauthorized access or information by intercepting these disclosed credentials. | |
| Title | curl: curl: Proxy credential disclosure via redirects to unauthenticated proxies | |
| Weaknesses | CWE-201 | |
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
MITRE
Status: PUBLISHED
Assigner: curl
Published:
Updated: 2026-05-13T09:05:31.000Z
Reserved: 2026-04-13T20:11:11.991Z
Link: CVE-2026-6253
Vulnrichment
No data.
NVD
No data.
Redhat