What’s Vulnerable › Vulnerabilities

CVE-2026-87865: knownhost callback mismatches key as missing

• Severity: high (CVSS 7.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-20 · updated 2026-10-30
• Weakness: CWE-295

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 products

• curl: from 8.22.0 through 8.22.0; from 8.21.0 through 8.21.0; from 8.20.0 through 8.20.0; from 8.19.0 through 8.19.0; from 8.18.0 through 8.18.0; from 8.17.0 through 8.17.0

References

• https://curl.se/docs/CVE-2026-87865.html
• https://curl.se/docs/CVE-2026-87865.json
• https://hackerone.com/reports/3975408
• https://hackerone.com/reports/3975408

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