Vulnerability · Published Oct 20, 2026 · Assigned by curl
CVE-2026-86414leaking host credentials to HTTP proxy
Critical 9.1
In plain English
A critical-severity security flaw in curl from curl. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 52% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)9.1Critical
Exploit odds (30 days)0.7%top 47.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official description
An HTTP proxy can trick libcurl into sending the origin's credentials (Basic password, or a Negotiate/Kerberos ticket) to the proxy itself, by answering the `CONNECT` tunnel request with 401 `WWW-Authenticate:` instead of the expected 407 `Proxy-Authenticate:`.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.23 | curl | 8.23.0-r0 | ALPINE-CVE-2026-86414 |
| Alpine:v3.24 | curl | 8.23.0-r0 | ALPINE-CVE-2026-86414 |
| Debian:12 | curl | no fix listed | DEBIAN-CVE-2026-86414 |
| Debian:13 | curl | no fix listed | DEBIAN-CVE-2026-86414 |
| Debian:14 | curl | no fix listed | DEBIAN-CVE-2026-86414 |
| Ubuntu:22.04:LTS | curl | 7.81.0-1ubuntu1.30 | USN-8932-1 |
| Ubuntu:22.04:LTS | curl | 7.81.0-1ubuntu1.30 | UBUNTU-CVE-2026-86414 |
| Ubuntu:24.04:LTS | curl | 8.5.0-2ubuntu10.16 | USN-8932-1 |
| Ubuntu:24.04:LTS | curl | 8.5.0-2ubuntu10.16 | UBUNTU-CVE-2026-86414 |
| Ubuntu:26.04:LTS | curl | 8.18.0-1ubuntu2.8 | USN-8927-1 |
| Ubuntu:26.04:LTS | curl | 8.18.0-1ubuntu2.8 | UBUNTU-CVE-2026-86414 |
| Ubuntu:26.10 | curl | 8.20.0-2ubuntu11.1 | USN-8927-2 |
| Ubuntu:26.10 | curl | 8.20.0-2ubuntu11.1 | UBUNTU-CVE-2026-86414 |
Affected products (as reported)
Weakness: CWE-201 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N