Playwright downloads and installs browsers without verifying the authenticity of the SSL certificate

Summary

Use of curl with the -k (or --insecure) flag in installer scripts allows attackers to deliver arbitrary executables via Man-in-the-Middle (MitM) attacks. This can lead to full system compromise, as the downloaded files are installed as privileged applications.

Details

The following scripts in the microsoft/playwright repository at commit `bee11cbc28f24bd18e726163d0b9b1571b4f26a8` use curl -k to fetch and install executable packages without verifying the authenticity of the SSL certificate:

• `packages/playwright-core/bin/reinstall_chrome_beta_mac.sh`
• `packages/playwright-core/bin/reinstall_chrome_stable_mac.sh`
• `packages/playwright-core/bin/reinstall_msedge_dev_mac.sh`
• `packages/playwright-core/bin/reinstall_msedge_beta_mac.sh`
• `packages/playwright-core/bin/reinstall_msedge_stable_mac.sh`

In each case, the shell scripts download a browser installer package using curl -k and immediately install it:

curl --retry 3 -o ./<pkg-file> -k <url>
sudo installer -pkg /tmp/<pkg-file> -target /

Disabling SSL verification (-k) means the download can be intercepted and replaced with malicious content.

PoC

A high-level exploitation scenario:

1. An attacker performs a MitM attack on a network where the victim runs one of these scripts. 2. The attacker intercepts the HTTPS request and serves a malicious package (for example, a trojaned browser installer). 3. Because curl -k is used, the script downloads and installs the attacker's payload without any certificate validation. 4. The attacker's code is executed with system privileges, leading to full compromise.

No special configuration is needed: simply running these scripts on any untrusted or hostile network is enough.

Impact

This is a critical Remote Code Execution (RCE) vulnerability due to improper SSL certificate validation (CWE-295: Improper Certificate Validation). Any user or automation running these scripts is at risk of arbitrary code execution as root/admin, system compromise, data theft, or persistent malware installation. The risk is especially severe because browser packages are installed with elevated privileges and the scripts may be used in CI/CD or developer environments.

Fix

• https://github.com/microsoft/playwright/commit/72c62d840247d9defd87c6beb0344d456794b570
• https://github.com/microsoft/playwright/pull/37532
• https://github.com/microsoft/playwright/releases/tag/v1.56.0

Credit

• This vulnerability was uncovered by tooling by Socket
• This vulnerability was confirmed by @evilpacket
• This vulnerability was reported by @JLLeitschuh at Socket

Disclosure

• September 10th, 2025 - Disclosed to Microsoft privately via https://github.com/microsoft/playwright/security/advisories/GHSA-gx27-2j22-qcx8
• September 11th, 2025 - Reported to Microsoft via MSRC Researcher Portal - https://msrc.microsoft.com/report/vulnerability/VULN-162854
• September 11th, 2025 - Microsoft closed report as "Complete - N/A"
• September 18th, 2025 - Following a LinkedIn Post