CVE-2026-10220Public exploitNetwork attack vector

Agent behavior manipulation via served plugin instructions

Published Jun 1, 2026 · Updated Jun 1, 2026

Prompt injection in Hermes Agent through 2026.4.30 allows remote attackers to alter agent behavior through plugin skill content. The _serve_plugin_skill() path detects known injection strings in SKILL.md but only logs a warning before skill_view() returns the instructions. Reachability requires an enabled plugin and selection of its skill content; the vendor classifies prompt injection and malicious plugin content as outside its security boundary.

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 Hermes Agent through 2026.4.30 allows remote attackers to alter agent behavior through plugin skill content. The _serve_plugin_skill() path detects known injection strings in SKILL.md but only logs a warning before skill_view() returns the instructions. Reachability requires an enabled plugin and selection of its skill content; the vendor classifies prompt injection and malicious plugin content as outside its security boundary.

The record

CVE
CVE-2026-10220
Published
Jun 1, 2026
Updated
Jun 1, 2026
Vendor
Nous Research
Product
Hermes Agent
Classifications
CWE-74, CWE-707
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

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

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=2026.4.0
  2. Affected versionversion=2026.4.1
  3. Affected versionversion=2026.4.10
  4. Affected versionversion=2026.4.11
  5. Affected versionversion=2026.4.12
  6. Affected versionversion=2026.4.13
  7. Affected versionversion=2026.4.14
  8. Affected versionversion=2026.4.15
  9. Affected versionversion=2026.4.16
  10. Affected versionversion=2026.4.17
  11. Affected versionversion=2026.4.18
  12. Affected versionversion=2026.4.19
  13. Affected versionversion=2026.4.2
  14. Affected versionversion=2026.4.20
  15. Affected versionversion=2026.4.21
  16. Affected versionversion=2026.4.22
  17. Affected versionversion=2026.4.23
  18. Affected versionversion=2026.4.24
  19. Affected versionversion=2026.4.25
  20. Affected versionversion=2026.4.26
  21. Affected versionversion=2026.4.27
  22. Affected versionversion=2026.4.28
  23. Affected versionversion=2026.4.29
  24. Affected versionversion=2026.4.3
  25. Affected versionversion=2026.4.30
  26. Affected versionversion=2026.4.4
  27. Affected versionversion=2026.4.5
  28. Affected versionversion=2026.4.6
  29. Affected versionversion=2026.4.7
  30. Affected versionversion=2026.4.8
  31. Affected versionversion=2026.4.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nous Research · Hermes Agentversion=2026.4.0; version=2026.4.1; version=2026.4.10; version=2026.4.11; version=2026.4.12; version=2026.4.13; version=2026.4.14; version=2026.4.15; version=2026.4.16; version=2026.4.17; version=2026.4.18; version=2026.4.19; version=2026.4.2; version=2026.4.20; version=2026.4.21; version=2026.4.22; version=2026.4.23; version=2026.4.24; version=2026.4.25; version=2026.4.26; version=2026.4.27; version=2026.4.28; version=2026.4.29; version=2026.4.3; version=2026.4.30; version=2026.4.4; version=2026.4.5; version=2026.4.6; version=2026.4.7; version=2026.4.8; version=2026.4.9

Published CVSS scores

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
7.3VulDBCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
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

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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