heymrun heym up to 0.0.74 Stdio Transport os command injection

Summaryinfo

A vulnerability marked as very critical has been reported in heymrun heym up to 0.0.74. Affected is an unknown function of the component Stdio Transport. Performing a manipulation results in os command injection. This vulnerability was named CVE-2026-67546. The attack may be initiated remotely. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in heymrun heym up to 0.0.74. It has been classified as very critical. This affects an unknown code of the component Stdio Transport. The manipulation with an unknown input leads to a os command injection vulnerability. CWE is classifying the issue as CWE-78. The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command before it is sent to a downstream component. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Heym builds and runs agentic systems and business-process automations on self-hosted infrastructure. Prior to version 0.0.75, the same POST /api/mcp/fetch-tools endpoint (any authenticated user, lowest role) also accepts the stdio transport, which spawns the attacker-supplied command with attacker-supplied args and an environment merged over os.environ. The process executes on the shared backend host before MCP protocol validation fails — so side effects fire regardless of whether the command speaks MCP. This is a distinct weakness class and exploit primitive from the SSRF (Advisory 2) on the same endpoint, and needs a different fix (role gating / opt-in trust boundary rather than egress controls). This issue has been patched in version 0.0.75.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-67546 since 07/29/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 11/11/2026). The attack technique deployed by this issue is T1202 according to MITRE ATT&CK.

Upgrading to version 0.0.75 eliminates this vulnerability.

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Productinfo

Vendor

• heymrun

Name

• heym

Version

• 0.0.1
• 0.0.2
• 0.0.3
• 0.0.4
• 0.0.5
• 0.0.6
• 0.0.7
• 0.0.8
• 0.0.9
• 0.0.10
• 0.0.11
• 0.0.12
• 0.0.13
• 0.0.14
• 0.0.15
• 0.0.16
• 0.0.17
• 0.0.18
• 0.0.19
• 0.0.20
• 0.0.21
• 0.0.22
• 0.0.23
• 0.0.24
• 0.0.25
• 0.0.26
• 0.0.27
• 0.0.28
• 0.0.29
• 0.0.30
• 0.0.31
• 0.0.32
• 0.0.33
• 0.0.34
• 0.0.35
• 0.0.36
• 0.0.37
• 0.0.38
• 0.0.39
• 0.0.40
• 0.0.41
• 0.0.42
• 0.0.43
• 0.0.44
• 0.0.45
• 0.0.46
• 0.0.47
• 0.0.48
• 0.0.49
• 0.0.50
• 0.0.51
• 0.0.52
• 0.0.53
• 0.0.54
• 0.0.55
• 0.0.56
• 0.0.57
• 0.0.58
• 0.0.59
• 0.0.60
• 0.0.61
• 0.0.62
• 0.0.63
• 0.0.64
• 0.0.65
• 0.0.66
• 0.0.67
• 0.0.68
• 0.0.69
• 0.0.70
• 0.0.71
• 0.0.72
• 0.0.73
• 0.0.74

Website

• Product: https://github.com/heymrun/heym/

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