Critical Vulnerability in mitmproxy: CVE-2026-40606
Summary
DEBIAN-CVE-2026-40606: ... Affects mitmproxy versions 6.0.2-1 – 8.1.1-4. No fix is published. How to fix ↓
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Background
mitmproxy is an open-source proxy tool that allows users to intercept, inspect, modify, and replay web traffic. It is widely used for debugging and testing web applications. The tool provides a rich set of features, including a web-based interface, scripting capabilities, and support for various protocols. However, recent findings have identified a vulnerability (CVE-2026-40606) that affects multiple Debian versions of mitmproxy, potentially exposing users to security risks.
Vulnerability Detail
CVE-2026-40606 is a vulnerability that arises from improper handling of certain inputs within the mitmproxy package. This flaw could allow an attacker to exploit the system by sending specially crafted requests, leading to unauthorized access or manipulation of sensitive data. The vulnerability affects all versions of mitmproxy available in Debian 11, 12, and 14, making it critical for users to address it promptly to avoid potential data breaches or service disruptions.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, users can limit access to the mitmproxy service by configuring firewall rules to restrict incoming connections. This can help mitigate the risk until a patch is applied. For example, you can use the following command to block external access:
sudo ufw deny from any to any port 8080'.
Conclusion
The CVE-2026-40606 vulnerability in mitmproxy poses significant risks to users of the tool across multiple Debian versions. It is crucial to update to the latest patched version to safeguard against potential exploits. Users are encouraged to implement workarounds if immediate updates are not feasible and to stay informed about security advisories.
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FAQ
CVE-2026-40606 is a vulnerability in the mitmproxy package that could allow attackers to exploit the system through specially crafted requests.
The vulnerability affects all versions of mitmproxy available in Debian 11, 12, and 14.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
If you cannot update immediately, consider implementing firewall rules to restrict access to the mitmproxy service as a temporary workaround.
More information can be found in the official Debian security advisories and on the Vulert website, which monitors open-source vulnerabilities.
References
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