curl · 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:`
Affects curlSource GCVE Database
Not known to be exploited · fixed in 7.35.0-1ubuntu2.20+esm24 : patch curl soon.
Data as of 28 Oct 2026, 22:28 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
- Patch
- Available – fixed in 7.35.0-1ubuntu2.20+esm24, 7.47.0-1ubuntu2.19+esm21, 7.58.0-2ubuntu3.24+esm15 +5
Exploitation evidence
Disclosed: evidence found.
CVE published 20 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Patches and advisories
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10curlpkg:deb/ubuntu/curl?arch=source&distro=stonkingOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTScurlpkg:deb/ubuntu/curl?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTScurlpkg:deb/ubuntu/curl?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 22.04 LTScurlpkg:deb/ubuntu/curl?arch=source&distro=jammyOther threats | Affected
| Fixed in
|
Ubuntu Pro 20.04 LTScurlpkg:deb/ubuntu/curl?arch=source&distro=esm-infra/focalOther threats | Affected
| Fixed in
|
Ubuntu Pro 18.04 LTScurlpkg:deb/ubuntu/curl?arch=source&distro=esm-infra/bionicOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
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:`.
References
- ubuntu.com/security/CVE-2026-86414 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-86414 (opens in a new tab)
- curl.se/docs/CVE-2026-86414.html (opens in a new tab)
- ubuntu.com/security/notices/USN-8927-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8927-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8932-1 (opens in a new tab)