CVE-2026-18996Public exploitNetwork attack vector

Authenticated file writes via safe-read shell misclassification

Published Aug 6, 2026 · Updated Aug 6, 2026

Authorization bypass in Cosmic Stack Mercury Agent 1.1.0 through 1.1.12 allows remote authenticated users to write host files. PermissionManager.checkShellCommand treats echo with shell redirection as a safe read, then run_command passes the unchanged string to a real shell. Reachability requires interactive approval mode and control over a run_command invocation; writes are limited to Mercury's execution context.

CVSS severity5.3
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Authorization bypass in Cosmic Stack Mercury Agent 1.1.0 through 1.1.12 allows remote authenticated users to write host files. PermissionManager.checkShellCommand treats echo with shell redirection as a safe read, then run_command passes the unchanged string to a real shell. Reachability requires interactive approval mode and control over a run_command invocation; writes are limited to Mercury's execution context.

The record

CVE
CVE-2026-18996
Published
Aug 6, 2026
Updated
Aug 6, 2026
Vendor
Cosmic Stack
Product
Mercury Agent
Classifications
CWE-266, T1059
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 6, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 6, 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=1.1.0
  2. Affected versionversion=1.1.1
  3. Affected versionversion=1.1.10
  4. Affected versionversion=1.1.11
  5. Affected versionversion=1.1.12
  6. Affected versionversion=1.1.2
  7. Affected versionversion=1.1.3
  8. Affected versionversion=1.1.4
  9. Affected versionversion=1.1.5
  10. Affected versionversion=1.1.6
  11. Affected versionversion=1.1.7
  12. Affected versionversion=1.1.8
  13. Affected versionversion=1.1.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Cosmic Stack · Mercury Agentversion=1.1.0; version=1.1.1; version=1.1.10; version=1.1.11; version=1.1.12; version=1.1.2; version=1.1.3; version=1.1.4; version=1.1.5; version=1.1.6; version=1.1.7; version=1.1.8; version=1.1.9

Published CVSS scores

5.7VulDBCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L/E:P/RL:X/RC:R
6.3VulDBCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
5.3VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N
6.5VulDBAV:N/AC:L/Au:S/C:P/I:P/A:P
2.1VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

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

Weakness, pattern, technique

CWE-266Incorrect Privilege Assignment
T1059Command and Scripting Interpreter

Public exploit references

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo