CVE-2026-107785 Crux Agent silently fails SKA preshared key rotation when SHA-512 peering is negotiated
Crux Agent fails to rotate WireGuard preshared keys correctly when SHA-512 is negotiated, potentially allowing decryption of traffic by quantum-capable attackers.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-107785?
CVE-2026-107785 is a medium-severity vulnerability in Sirius Computer, Inc. Crux Agent, published on 9 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Crux Agent from 1.9.0 before 2.0.3 uses the full SKA bilocation key as the WireGuard preshared key. When a peering session negotiates use of SHA-512, the key produced is 64 bytes instead of the 32 bytes WireGuard requires. The agent does not validate this size; instead it attempts to use the `wg set` command to update the live tunnel, and write the invalid key to the WireGuard configuration file. The update fails, so the live tunnel keeps using its previous preshared key until the tunnel is shut down. The tunnel will fail to start when restarted.
For a peer which has never successfully negotiated a 32-byte bilocation key in a Crux C2 organization which has the "Enforce SKA Use" setting turned off, no preshared key will be set for the tunnel. Therefore, an attacker who is able to intercept and store the peer's traffic, and has access (or will have access) to a cryptographically relevant quantum computer, will be able to decrypt the tunnel.
Which versions are affected by CVE-2026-107785?
How do I fix CVE-2026-107785?
No fix has been published for CVE-2026-107785 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-107785 being exploited?
There is no known exploitation of CVE-2026-107785 in the wild and no public exploit code.
Sources
Also known as GHSA-jm3h-x845-c42w.