CVE-2026-7168 Details
Description
Successfully using libcurl to do a transfer over a specific HTTP proxy (`proxyA`) with **Digest** authentication and then changing the proxy host to a second one (`proxyB`) for a second transfer, reusing the same handle, makes libcurl wrongly pass on the `Proxy-Authorization:` header field meant for `proxyA`, to `proxyB`.
A vulnerability exists in libcurl versions 7.12.0 through 8.19.0, where the library improperly manages Digest authentication headers when switching between HTTP proxies. Specifically, if a transfer is completed using one proxy (proxyA) and the same handle is reused to transfer data through a second proxy (proxyB), libcurl erroneously transmits the Proxy-Authorization header intended for proxyA to proxyB. This flaw allows an attacker-controlled proxyB to impersonate the client to proxyA by replaying the intercepted authentication header, which contains valid credentials. Although the request details to proxyB do not disclose proxyA's identity, this vulnerability could still be exploited under certain conditions.
Users are advised to upgrade libcurl to version 8.20.0, apply the available patch, or avoid reusing handles when changing proxies.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed May 13, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://hackerone.com/reports/3697719 | CISA-ADP | ExploitIssue Tracking |
| https://curl.se/docs/CVE-2026-7168.html | curl | PatchVendor Advisory |
| https://curl.se/docs/CVE-2026-7168.json | curl | Vendor Advisory |
| https://hackerone.com/reports/3697719 | curl | ExploitIssue Tracking |
| http://www.openwall.com/lists/oss-security/2026/04/29/14 | CVE | Mailing ListPatch |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-294 | Authentication Bypass by Capture-replay | [email protected] |
| CWE-294 | Authentication Bypass by Capture-replay | curl |
Affected Products
| Product | Versions |
|---|---|
| haxx curl | >= 7.12.0, < 8.20.0 |
CPE
Remediation
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Change History
9 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 15, 2026 | CVE Modified | curl |
| Sep 15, 2026 | CVE Modified | CVE |
| Sep 15, 2026 | CVE Modified | CISA-ADP |
| Jun 17, 2026 | CVE Modified | curl |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| May 14, 2026 | Initial Analysis | [email protected] |
| May 13, 2026 | CVE Modified | CISA-ADP |
| May 13, 2026 | CVE Modified | CVE |
| May 13, 2026 | New CVE Received | curl |