OpenSSH VerifyHostKeyDNS Machine-in-the-Middle Host Verification Bypass
CVE-2025-26465 is an OpenSSH client-side host verification vulnerability affecting OpenSSH versions 6.8p1 through 9.9p1 when the VerifyHostKeyDNS option is enabled. The flaw is caused by incorrect handling of error codes during host key verification, which can allow an on-path attacker to impersonate a legitimate SSH server under specific conditions. Multiple sources in the provided content describe this as a logic error in ssh(1) that permits a malicious intermediary to bypass expected host authenticity checks and complete a machine-in-the-middle attack. The content also notes that successful exploitation requires the attacker to first exhaust the client’s memory resources, which raises attack complexity.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
No valid public exploits. Mallory filtered out 2 candidates as fakes, detection scripts, or README-only repos.
All candidate exploits were filtered out by Mallory's validation.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
16 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A known SSH/OpenSSH vulnerability present on the operator's server, mentioned as part of the host's unpatched exposure.
An OpenSSH man-in-the-middle vulnerability identified on the compromised Spanish server used to host the final payload.
An OpenSSH vulnerability that can enable an active machine-in-the-middle (MitM) attack under certain conditions.
Unknown (listed as a trending CVE affecting Western Digital; no technical details provided in the content).
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.