CVE-2026-26701 — Hermes Agent — sandbox escape via tool definition injection

Summary

Hermes Agent's tool loader did not validate sandbox declarations against a schema. A malicious tool definition (loaded from a community marketplace) could declare an empty sandbox block, effectively disabling the sandbox for that tool's execution. Patched in 2026.4.4.

Details

CVE ID	CVE-2026-26701
Severity	high (7.6)
CVSS vector	AV:L/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N
Published	2026-04-26
Patched	not yet
Affected versions	2026.4.0 – 2026.4.3
Fixed in	2026.4.4
Exploited in the wild	no known exploitation

Affected projects

Hermes Agent

What to do

If you run an affected version: upgrade to 2026.4.4 immediately. Do not delay this for convenience reasons.
Rotate any credentials that may have been exposed via the affected component.
Audit your logs for indicators of exploitation — unexpected outbound traffic, anomalous tool calls, unfamiliar authenticated sessions.
If exploitation is confirmed, treat the host as compromised: rebuild from a clean image, rotate every secret on the host, audit lateral movement.

Sources

NIST NVD: CVE-2026-26701 on NVD

See also: all CVEs, tracked agents, methodology.