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Vulnerability · Published May 24, 2026 · Assigned by VulDB

CVE-2026-9354NousResearch hermes-agent Slack Agent/Mattermost Agent escape output

Medium 6.5

In plain English

A medium-severity injection in hermes-agent from NousResearch. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 27% of all known vulnerabilities).

Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.3%top 72.8% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

A vulnerability was detected in NousResearch hermes-agent up to 2026.4.16. The affected element is an unknown function of the component Slack Agent/Mattermost Agent. The manipulation of the argument format_message results in escaping of output. The attack can be executed remotely. The exploit is now public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

Affected products (as reported)

VendorProductVersions
NousResearch hermes-agent 2026.4.02026.4.12026.4.22026.4.32026.4.42026.4.52026.4.62026.4.7

Weakness: CWE-116, CWE-74 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L/E:P/RL:X/RC:R

References