CVE-2026-9366Public exploit

Tool execution via context-scanner regex bypass

Published May 24, 2026 · Updated May 24, 2026

Prompt injection in Nous Research Hermes Agent 2026.4.23 allows context-dependent attackers to steer tools through poisoned project-context files. The _scan_context_content function in agent/prompt_builder.py uses single-qualifier regular expressions, returns unmatched content unchanged, and loaders append it to the system prompt. Exploitation requires a user to run Hermes in an untrusted repository; bypass text can then direct terminal, file, memory, or delegation tools with that user's access.

CVSS severity7.3
High
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Prompt injection in Nous Research Hermes Agent 2026.4.23 allows context-dependent attackers to steer tools through poisoned project-context files. The _scan_context_content function in agent/prompt_builder.py uses single-qualifier regular expressions, returns unmatched content unchanged, and loaders append it to the system prompt. Exploitation requires a user to run Hermes in an untrusted repository; bypass text can then direct terminal, file, memory, or delegation tools with that user's access.

The record

CVE
CVE-2026-9366
Published
May 24, 2026
Updated
May 24, 2026
Vendor
Nous Research
Product
Hermes Agent
Classifications
CWE-74, CWE-707, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 24, 2026CVE publishedPublication date reported by the CVE source.
  2. May 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2026.4.23

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Nous Research · Hermes Agentversion=2026.4.23

Published CVSS scores

7.3VulDBCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
5.5VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
7.5VulDBAV:N/AC:L/Au:N/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
CWE-707Improper Neutralization
T1204.002Malicious File

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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