Legcord CVE-2026-105293

Exploitation requires the attacker to already be executing script within the Discord origin inside Legcord (for example via XSS in the Discord web content), which the CVSS AT:P requirement and AC:H reflect - this is not exploitable against a passive, non-interacting client with no script foothold. Given that foothold, the attacker abuses the themes.folder, themes.uninstall, and themes.install IPC handlers (ipc.ts / themes.ts) by supplying theme ids that are not validated against the themes directory, enabling traversal outside it. The vulnerability affects Legcord versions 1.1.0 through 1.3.0; the primary limiting factor is the need for a separate renderer script-execution capability, after which no further authentication is required (PR:N).

CVSS 4.0 rates this 9.2 (Critical) with full confidentiality, integrity, and availability impact (VC:H/VI:H/VA:H), consistent with the ability to launch local executables, recursively delete directories, and write arbitrary files outside the themes directory - effectively code execution on the host. However, the vector itself tempers raw severity: AC:H and AT:P indicate the attack is not trivially repeatable and depends on a specific precondition, and the description makes that precondition explicit - the attacker must already be running script in the Discord origin (e.g., via XSS). This is therefore a chained/secondary vulnerability rather than a standalone remote-unauthenticated RCE, which meaningfully narrows real-world exploitability. No EPSS score was supplied, the CVE is not listed in CISA KEV, and no public proof-of-concept is referenced, so there is no public exploit identified at time of analysis and no evidence of active exploitation. SSVC-style read: technical impact is total, but automatability is low given the required XSS foothold and the local-execution context of a desktop app. Net: a genuinely serious design flaw worth prompt patching for Legcord users, but its practical priority is gated by the prevalence of the product (a niche third-party Discord client) and by the need for a separate script-execution primitive in the Discord renderer.

An attacker who can execute JavaScript in Legcord's Discord renderer - for example through a cross-site scripting flaw in the Discord web content or a malicious embedded resource - calls the themes.folder, themes.install, or themes.uninstall IPC handlers with a theme id containing path-traversal sequences. Because the id is not validated against the themes directory, the handler operates on attacker-chosen paths, letting the attacker launch a local executable, delete directories recursively, or write files anywhere the Legcord process can reach, escalating a renderer-level script foothold into host code execution. No public proof-of-concept is referenced, and the high attack complexity reflects the need for that initial script-execution primitive.