Vulnerability · Published Oct 20, 2026 · Assigned by curl
CVE-2026-87865knownhost callback mismatches key as missing
High 7.4
In plain English
A high-severity improper certificate validation in curl from curl. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 49% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)7.4High
Exploit odds (30 days)0.6%top 50.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official description
When libcurl uses libssh2 with a hashed `known_hosts` file, an unrelated initial entry can cause host key validation to report a key *mismatch* as a *missing* key to the `CURLOPT_SSH_KEYFUNCTION` callback.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.23 | curl | 8.23.0-r0 | ALPINE-CVE-2026-87865 |
| Alpine:v3.24 | curl | 8.23.0-r0 | ALPINE-CVE-2026-87865 |
| Debian:12 | curl | no fix listed | DEBIAN-CVE-2026-87865 |
| Debian:13 | curl | no fix listed | DEBIAN-CVE-2026-87865 |
| Debian:14 | curl | no fix listed | DEBIAN-CVE-2026-87865 |
| 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-2026-87865 |
| Ubuntu:26.10 | curl | 8.20.0-2ubuntu11.1 | USN-8927-2 |
| Ubuntu:26.10 | curl | 8.20.0-2ubuntu11.1 | UBUNTU-CVE-2026-87865 |
Affected products (as reported)
Weakness: CWE-295 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N