CVE-2026-54548 kas: Persistent SSH Host Key Checking Disablement
kas disables SSH host key checking globally, allowing man-in-the-middle attacks on subsequent SSH sessions for the local user.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-54548?
CVE-2026-54548 is a low-severity vulnerability in siemens kas, published on 26 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
kas is a setup tool for bitbake based projects. Prior to 5.4, internal SSH key setup triggered by SSH_PRIVATE_KEY or SSH_PRIVATE_KEY_FILE creates ~/.ssh/config when no user-specific SSH configuration exists and adds a global Host * rule containing StrictHostKeyChecking no. In kas/libcmds.py, ssh_no_host_key_check() runs without checking ctx.managed_env, so the setting persists after kas exits and affects future SSH sessions by the same local user, extending beyond the intended short-lived continuous integration environment. A later SSH connection can therefore accept an attacker-controlled host key without verification, increasing the risk of a man-in-the-middle attack that compromises session confidentiality or integrity. This issue is fixed in version 5.4.
Weakness: CWE-295
Which versions are affected by CVE-2026-54548?
3 open source packages ship an affected version, including kas.
| Package | Affected | Fixed in |
|---|---|---|
kas PyPI | All versions | 5.4 |
kas PyPI | All versions | 5.4 |
kas PyPI | All versions | 5.4 |
How do I fix CVE-2026-54548?
Upgrade kas to 5.4 or later.
Is CVE-2026-54548 being exploited?
There is no known exploitation of CVE-2026-54548 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-54548, GHSA-mv8m-v9v6-5f94, PYSEC-2026-3855, UBUNTU-CVE-2026-54548.