CVE record: Hermes Agent's bundled MCP catalog pointed at a mutable branch, making a third-party repo compromise an RCE path

VulnCheck published CVE-2026-82021 on 2026-08-28 against Hermes Agent, the NousResearch agent framework whose repository shows roughly 239,000 GitHub stars. The finding is a supply-chain shape rather than a parser bug: the agent's bundled MCP catalog referenced a third-party upstream repository by mutable branch instead of a pinned commit SHA. An attacker who compromised that upstream could ship arbitrary code to every agent that resolved the catalog entry, which the record scores 9.0 critical on CVSS 4.0.

The fix predates the record by five and a half weeks: v0.19.0, released 2026-07-20 under the project's calendar tag v2026.7.20, moved off the mutable reference. The affected range is narrow and exactly stated, 0.18.2 up to that release.

A second record against the same project arrived on 2026-09-01 from VulDB: CVE-2026-84289, a 5.3 medium, describes uncontrolled memory allocation in the list_tools function of tools/mcp_tool.py. It lists 0.18.0 through 0.18.2 as affected and names no fixed version; the project's releases have since moved to v0.21.0. The two records carry different weights, a coordinated CNA disclosure with a shipped fix against a database entry with no vendor response on file, and are best read separately.

Pinning by SHA rather than branch is the standing remedy for consume-a-repo supply chains, and MCP catalogs, which exist to tell agents what code to run, concentrate exactly that risk.