CVE-2024-41138 Overview
CVE-2024-41138 is a library injection vulnerability in the com.microsoft.teams2.modulehost.app helper application of Microsoft Teams (work or school) version 24046.2813.2770.1094 for macOS. A specially crafted dynamic library can leverage the Teams helper's access privileges, leading to a permission bypass. An attacker who can place a malicious library on the target system can inject it into the helper process and inherit Teams's macOS Transparent Consent and Control (TCC) permissions, including microphone, camera, and accessibility access.
Critical Impact
A malicious application on macOS can inject a library into the Teams helper and abuse Teams's existing TCC permissions to access protected resources without prompting the user.
Affected Products
- Microsoft Teams (work or school) for macOS, version 24046.2813.2770.1094
- macOS installations of the Teams helper app com.microsoft.teams2.modulehost.app
- Endpoints where the Teams client holds TCC permissions (microphone, camera, accessibility)
Discovery Timeline
- 2024-12-18 - CVE-2024-41138 published to the National Vulnerability Database
- 2025-08-26 - Last updated in NVD database
Technical Details for CVE-2024-41138
Vulnerability Analysis
The issue is tracked under CWE-347: Improper Verification of Cryptographic Signature. The Teams helper application com.microsoft.teams2.modulehost.app loads dynamic libraries without enforcing the runtime signature constraints that macOS provides for hardened applications. As a result, a library not signed by Microsoft can be loaded into the helper process at launch.
Once loaded, the injected library runs inside a process that Teams has already been granted user-approved TCC permissions for. The library inherits microphone, camera, screen recording, or accessibility entitlements without triggering a new user consent prompt. This converts a local code execution primitive into a privacy and permission bypass on macOS.
Additional technical context is available in the Talos Intelligence Vulnerability Report TALOS-2024-1991.
Root Cause
The Teams helper binary is not built with the Hardened Runtime library validation flag enforced for third-party libraries. macOS therefore permits the loader to map an attacker-supplied dylib into the process address space. Improper verification of the library's code signature against Microsoft's Team ID is the underlying defect.
Attack Vector
An attacker with the ability to write a file to a path read by the Teams helper, or who can persuade a user to run a malicious application, drops a crafted .dylib and triggers helper startup. The dylib executes with the helper's identity and accesses microphone, camera, or other TCC-gated resources that Teams has already been authorized to use.
The vulnerability manifests in the dynamic loader path of the Teams helper. No exploit code or public proof-of-concept is referenced in the advisory. See the Talos vulnerability report for technical details.
Detection Methods for CVE-2024-41138
Indicators of Compromise
- Unexpected .dylib files placed adjacent to com.microsoft.teams2.modulehost.app or in writable directories referenced by DYLD_* environment variables
- Child processes of Teams accessing the microphone, camera, or accessibility APIs without a corresponding user action
- Modifications to the Teams application bundle or its helper executables outside of an official Microsoft AutoUpdate session
Detection Strategies
- Monitor posix_spawn and dlopen events targeting the Teams helper bundle and alert on libraries not signed by Microsoft's Team ID UBF8T346G9
- Inspect codesign --verify --deep --strict results for the Teams bundle on managed macOS endpoints and flag drift
- Correlate TCC database access events (/Library/Application Support/com.apple.TCC/TCC.db) with the loading parent process to identify abuse of inherited permissions
Monitoring Recommendations
- Centralize macOS Endpoint Security Framework (ESF) telemetry covering ES_EVENT_TYPE_NOTIFY_MMAP and process exec events for Teams helpers
- Track installation of unsigned or ad-hoc signed libraries within user ~/Library paths used by Microsoft Teams
- Alert on Teams helper processes spawning shells, executing scripting interpreters, or making outbound connections to non-Microsoft infrastructure
How to Mitigate CVE-2024-41138
Immediate Actions Required
- Upgrade Microsoft Teams for macOS to a build later than 24046.2813.2770.1094 distributed through Microsoft AutoUpdate
- Inventory macOS endpoints running the affected build and prioritize remediation on systems where Teams holds microphone, camera, or screen recording permissions
- Review TCC permission grants for Teams and revoke any that are not required for business workflows
Patch Information
Microsoft addressed the issue in a subsequent Teams for macOS release. Refer to the Talos Intelligence Vulnerability Report TALOS-2024-1991 for the fixed version reference and confirm the installed build using Microsoft Teams.app/Contents/Info.plistCFBundleVersion.
Workarounds
- Restrict local user write access to directories from which Teams loads supporting components, and enforce filesystem integrity monitoring on the Teams bundle
- Deploy a macOS configuration profile that limits Teams TCC permissions to only the capabilities required by the organization
- Remove Microsoft Teams from endpoints that do not require it until the patched version is deployed
# Verify the installed Microsoft Teams version and code signature on macOS
/usr/bin/defaults read "/Applications/Microsoft Teams.app/Contents/Info.plist" CFBundleVersion
/usr/bin/codesign --verify --deep --strict --verbose=2 "/Applications/Microsoft Teams.app"
/usr/bin/codesign -dv --entitlements - "/Applications/Microsoft Teams.app/Contents/Frameworks/com.microsoft.teams2.modulehost.app"
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
