CVE-2026-54548 is a low-severity (CVSS 3.3) CWE-295 vulnerability in kas. O3 Security confirms whether CVE-2026-54548 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
kas Persistently Disables SSH Host Key Checking
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-54548.
Real-World Exposure
kasReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Summary
kas persistently disables SSH host key checking for the invoking user when internal SSH key setup is triggered via SSH_PRIVATE_KEY or SSH_PRIVATE_KEY_FILE and no user-specific SSH configuration file exists so far.
When this path is used, kas creates ~/.ssh/config with a global Host * rule containing StrictHostKeyChecking no. This was intended to ease the use of kas in short-lived CI environments that lack a pre-configured set of known hosts. In case a local user had no SSH configuration file so far, this approach weakens SSH host authenticity verification beyond the lifetime and scope of the kas command, increasing the risk of successful man-in-the-middle attacks against future SSH connections made by the same user.
Patches
Such SSH configurations were created since the very first public release. The issue is addressed now by commit <FILLME> which is part of kas version 5.4.
Workarounds
Since kas 2.6.3, a local user's SSH configuration is only written if it didn't exist before. From that version on, the issue can be avoided by creating an own ~/.ssh/config prior to calling kas. If kas was already called, ~/.ssh/config should be inspected and undesired settings created by kas should be removed.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | kas | all versions | 5.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for kas. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update kas to 5.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54548 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-54548 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-54548. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-54548 in your dependencies?
O3 detects CVE-2026-54548 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.