Medium · CVSS 6.3CVE-2026-107785

Crux Agent silently fails SKA preshared key rotation when SHA-512 peering is negotiatedCVE-2026-107785

Answer in brief

CVE-2026-107785 records a Medium severity (CVSS 6.3) vulnerability in Crux Agent silently fails SKA preshared key rotation when SHA-512 peering is negotiated. The current sources do not mark it as known exploited. The current feed maps Sirius Computer, Inc./Crux Agent (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Oct 9, 2026Updated Oct 9, 2026Source checked Oct 9, 2026First seen by HOL Oct 9, 2026Material review Oct 9, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 6.3
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 6.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Sirius Computer, Inc./Crux Agent (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Sirius Computer, Inc./Crux Agentgeneric	>=1.9.0 <2.0.3	2.0.3

Recommended response

Check inventory. Check lockfiles and deployed manifests for Sirius Computer, Inc./Crux Agent.
Review the reported fix. Source-reported solution: Upgrade to Crux Agent 2.0.3 or later, which truncates the SKA key to the 32 bytes WireGuard requires. As a workaround, remove any custom settings for "Hash Function" in the agent's configuration (so as to use the default SHA-256 hash function).

Evidence timeline and material changes

Published upstream
Oct 9, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Oct 9, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Oct 9, 2026

Sources and claim methodology

Source referencesirius.computer

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.