CVE-2026-82021
Hermes Agent 0.18.2 prior to 0.19.0 contains a supply chain vulnerability in its bundled MCP catalog that allows a remote attacker to execute arbitrary code by compromising a third-party upstream repository referenced via a mutable branch rather than a…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.23%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
Hermes Agent 0.18.2 prior to 0.19.0 contains a supply chain vulnerability in its bundled MCP catalog that allows a remote attacker to execute arbitrary code by compromising a third-party upstream repository referenced via a mutable branch rather than a pinned commit SHA. An attacker who compromises the upstream repository can propagate malicious code to every host that installs the affected catalog entry, with no further action required by the operator.
- CVSS 4.0
- 9.0 CRITICALCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.23% probability · 13th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-494
- Source
- disclosure@vulncheck.com
References
- https://github.com/NousResearch/hermes-agent/commit/9df5f879b4a5925c0f8f947e7e16ed8e845932c3
- https://github.com/NousResearch/hermes-agent/pull/64463
- https://github.com/NousResearch/hermes-agent/releases/tag/v2026.7.20
- https://www.vulncheck.com/advisories/hermes-agent-mcp-catalog-supply-chain-rce-via-mutable-branch-reference
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.