Loading vulnerability…
CVE-2026-55427 is a high-severity injection vulnerability in Coder's coder config-ssh functionality. In affected versions, coder config-ssh wrote server-supplied SSH settings, specifically HostnameSuffix and SSHConfigOptions, into the local user's ~/.ssh/config file without sanitizing embedded newlines or otherwise restricting injected directives. Because these values originated from the Coder server, a malicious or compromised server, or an attacker able to tamper with those values, could cause arbitrary SSH configuration entries to be written into the user's SSH client configuration. This is effectively an SSH configuration injection issue that can introduce attacker-controlled directives such as ProxyCommand and alter the behavior of subsequent SSH connections from the developer workstation.
Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
~/.ssh/config. This can affect not only Coder-related SSH connections but potentially other SSH connections made by the user, depending on the injected directives and matching rules. In practical terms, injected directives such as ProxyCommand can lead to arbitrary code execution on the developer workstation with the privileges of the local user. It can also enable traffic interception, redirection, credential exposure, or broader compromise of SSH-based workflows originating from that host.If you can’t patch tonight, do this now.
coder config-ssh --dry-run before applying changes. More generally, avoid applying SSH configuration generated from untrusted or potentially compromised Coder deployments, and restrict administrative control over the HostnameSuffix and SSHConfigOptions settings. If compromise is suspected, manually audit and clean the user's ~/.ssh/config for injected directives.Patch, then assume compromise.
HostnameSuffix and SSHConfigOptions against a strict character set that rejects newlines and other control characters, preventing arbitrary directive injection into ~/.ssh/config. After upgrading, review existing ~/.ssh/config files for unauthorized or unexpected directives that may have been previously written.No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
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.
3 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
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.