knowns CVE-2026-86540

The victim must be running knowns before v0.30.0 and must open a project directory containing a .knowns/config.json with a malicious value in settings.lsp.languages.[langID].binary (for example, settings.lsp.languages.go.binary set to /bin/sh or any attacker-controlled path). The malicious repository must be present on the victim's local filesystem, typically via clone or download. The exploit triggers automatically during LSP initialization on project open, requiring no further user action within the application. Limiting factors: the victim must specifically use knowns rather than a mainstream editor; the malicious config file must reach disk before the project is opened; and the victim must be running a version prior to 0.30.0. No special system privileges or non-default OS configuration are required on the victim side.

The vendor-issued CVSS 4.0 score of 8.5 with vector AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H accurately represents the real-world risk profile. The local attack vector (AV:L) is the principal limiting factor: the malicious config must reach the victim's filesystem, typically via a repository clone or download. However, the UI:P metric correctly captures that the only user interaction required is opening a project in knowns - a routine, habitual developer action that provides minimal friction. No EPSS score or KEV listing is available for this CVE, and no public exploit code is identified at time of analysis; these signals moderate urgency for most teams. That said, the fully public patch diff and GHSA advisory lower the barrier to exploit development significantly, and the pattern of triggering code execution by opening a malicious repository is well-understood from analogous IDE-level supply-chain attacks. Developer-facing teams that regularly open repositories from external contributors or open-source projects represent the highest-risk population, and any team in that situation - whether a large enterprise or a small development shop - should treat this as a prompt patch priority given the zero-friction exploitation path once a malicious repository reaches disk.

An attacker publishes or contributes a repository containing a .knowns/config.json that sets a language server binary (for example, the Go language entry) to /bin/sh or another attacker-controlled executable. When a developer running knowns before 0.30.0 clones and opens this repository, knowns automatically invokes the malicious binary twice during LSP initialization - executing arbitrary code under the developer's account with no further interaction. No public exploit code is identified at time of analysis, but the patch diff fully documents both vulnerable call sites.