proxy credentials leak over redirect-to proxy
Summary
| CVE | CVE-2026-6253 |
|---|---|
| State | PUBLISHED |
| Assigner | curl |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-05-13 13:01:56 UTC |
| Updated | 2026-05-14 13:40:53 UTC |
| 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 |
Risk And Classification
Primary CVSS: v3.1 5.9 MEDIUM from ADP
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS: 0.000300000 probability, percentile 0.087850000 (date 2026-05-25)
Problem Types: CWE-522 | CWE-522 Insufficiently Protected Credentials
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | ADP | DECLARED | 5.9 | MEDIUM | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | Secondary | 5.9 | MEDIUM | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
HighPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
NoneAvailability
HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD Known Affected Configurations (CPE 2.3)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Curl | Curl | affected 8.19.0 8.19.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.18.0 8.18.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.17.0 8.17.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.16.0 8.16.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.15.0 8.15.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.14.1 8.14.1 semver | Not specified |
| CNA | Curl | Curl | affected 8.14.0 8.14.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.13.0 8.13.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.12.1 8.12.1 semver | Not specified |
| CNA | Curl | Curl | affected 8.12.0 8.12.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.11.1 8.11.1 semver | Not specified |
| CNA | Curl | Curl | affected 8.11.0 8.11.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.10.1 8.10.1 semver | Not specified |
| CNA | Curl | Curl | affected 8.10.0 8.10.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.9.1 8.9.1 semver | Not specified |
| CNA | Curl | Curl | affected 8.9.0 8.9.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.8.0 8.8.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.7.1 8.7.1 semver | Not specified |
| CNA | Curl | Curl | affected 8.7.0 8.7.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.6.0 8.6.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.5.0 8.5.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.4.0 8.4.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.3.0 8.3.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.2.1 8.2.1 semver | Not specified |
| CNA | Curl | Curl | affected 8.2.0 8.2.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.1.2 8.1.2 semver | Not specified |
| CNA | Curl | Curl | affected 8.1.1 8.1.1 semver | Not specified |
| CNA | Curl | Curl | affected 8.1.0 8.1.0 semver | Not specified |
| CNA | Curl | Curl | affected 8.0.1 8.0.1 semver | Not specified |
| CNA | Curl | Curl | affected 8.0.0 8.0.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.88.1 7.88.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.88.0 7.88.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.87.0 7.87.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.86.0 7.86.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.85.0 7.85.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.84.0 7.84.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.83.1 7.83.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.83.0 7.83.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.82.0 7.82.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.81.0 7.81.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.80.0 7.80.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.79.1 7.79.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.79.0 7.79.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.78.0 7.78.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.77.0 7.77.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.76.1 7.76.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.76.0 7.76.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.75.0 7.75.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.74.0 7.74.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.73.0 7.73.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.72.0 7.72.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.71.1 7.71.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.71.0 7.71.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.70.0 7.70.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.69.1 7.69.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.69.0 7.69.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.68.0 7.68.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.67.0 7.67.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.66.0 7.66.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.65.3 7.65.3 semver | Not specified |
| CNA | Curl | Curl | affected 7.65.2 7.65.2 semver | Not specified |
| CNA | Curl | Curl | affected 7.65.1 7.65.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.65.0 7.65.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.64.1 7.64.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.64.0 7.64.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.63.0 7.63.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.62.0 7.62.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.61.1 7.61.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.61.0 7.61.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.60.0 7.60.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.59.0 7.59.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.58.0 7.58.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.57.0 7.57.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.56.1 7.56.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.56.0 7.56.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.55.1 7.55.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.55.0 7.55.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.54.1 7.54.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.54.0 7.54.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.53.1 7.53.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.53.0 7.53.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.52.1 7.52.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.52.0 7.52.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.51.0 7.51.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.50.3 7.50.3 semver | Not specified |
| CNA | Curl | Curl | affected 7.50.2 7.50.2 semver | Not specified |
| CNA | Curl | Curl | affected 7.50.1 7.50.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.50.0 7.50.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.49.1 7.49.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.49.0 7.49.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.48.0 7.48.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.47.1 7.47.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.47.0 7.47.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.46.0 7.46.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.45.0 7.45.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.44.0 7.44.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.43.0 7.43.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.42.1 7.42.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.42.0 7.42.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.41.0 7.41.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.40.0 7.40.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.39.0 7.39.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.38.0 7.38.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.37.1 7.37.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.37.0 7.37.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.36.0 7.36.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.35.0 7.35.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.34.0 7.34.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.33.0 7.33.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.32.0 7.32.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.31.0 7.31.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.30.0 7.30.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.29.0 7.29.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.28.1 7.28.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.28.0 7.28.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.27.0 7.27.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.26.0 7.26.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.25.0 7.25.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.24.0 7.24.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.23.1 7.23.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.23.0 7.23.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.22.0 7.22.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.21.7 7.21.7 semver | Not specified |
| CNA | Curl | Curl | affected 7.21.6 7.21.6 semver | Not specified |
| CNA | Curl | Curl | affected 7.21.5 7.21.5 semver | Not specified |
| CNA | Curl | Curl | affected 7.21.4 7.21.4 semver | Not specified |
| CNA | Curl | Curl | affected 7.21.3 7.21.3 semver | Not specified |
| CNA | Curl | Curl | affected 7.21.2 7.21.2 semver | Not specified |
| CNA | Curl | Curl | affected 7.21.1 7.21.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.21.0 7.21.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.20.1 7.20.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.20.0 7.20.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.19.7 7.19.7 semver | Not specified |
| CNA | Curl | Curl | affected 7.19.6 7.19.6 semver | Not specified |
| CNA | Curl | Curl | affected 7.19.5 7.19.5 semver | Not specified |
| CNA | Curl | Curl | affected 7.19.4 7.19.4 semver | Not specified |
| CNA | Curl | Curl | affected 7.19.3 7.19.3 semver | Not specified |
| CNA | Curl | Curl | affected 7.19.2 7.19.2 semver | Not specified |
| CNA | Curl | Curl | affected 7.19.1 7.19.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.19.0 7.19.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.18.2 7.18.2 semver | Not specified |
| CNA | Curl | Curl | affected 7.18.1 7.18.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.18.0 7.18.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.17.1 7.17.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.17.0 7.17.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.16.4 7.16.4 semver | Not specified |
| CNA | Curl | Curl | affected 7.16.3 7.16.3 semver | Not specified |
| CNA | Curl | Curl | affected 7.16.2 7.16.2 semver | Not specified |
| CNA | Curl | Curl | affected 7.16.1 7.16.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.16.0 7.16.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.15.5 7.15.5 semver | Not specified |
| CNA | Curl | Curl | affected 7.15.4 7.15.4 semver | Not specified |
| CNA | Curl | Curl | affected 7.15.3 7.15.3 semver | Not specified |
| CNA | Curl | Curl | affected 7.15.2 7.15.2 semver | Not specified |
| CNA | Curl | Curl | affected 7.15.1 7.15.1 semver | Not specified |
| CNA | Curl | Curl | affected 7.15.0 7.15.0 semver | Not specified |
| CNA | Curl | Curl | affected 7.14.1 7.14.1 semver | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| hackerone.com/reports/3669637 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | hackerone.com | Exploit, Issue Tracking, Third Party Advisory |
| www.openwall.com/lists/oss-security/2026/04/29/11 | af854a3a-2127-422b-91ae-364da2661108 | www.openwall.com | Mailing List, Patch, Third Party Advisory |
| curl.se/docs/CVE-2026-6253.html | 2499f714-1537-4658-8207-48ae4bb9eae9 | curl.se | Patch, Vendor Advisory |
| curl.se/docs/CVE-2026-6253.json | 2499f714-1537-4658-8207-48ae4bb9eae9 | curl.se | Vendor Advisory |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Dwij Mehta (O2 Lab (en)
CNA: Texas A&M University) (en)
CNA: Daniel Stenberg (en)
There are currently no legacy QID mappings associated with this CVE.