HTTP Response Splitting Affecting microdot package, versions [,2.6.1)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-MICRODOT-16431739
- published6 May 2026
- disclosed5 May 2026
- creditLuan Tran
Introduced: 5 May 2026
CVE-2026-42874 (opens in a new tab)How to fix?
Upgrade microdot to version 2.6.1 or higher.
Overview
microdot is a The impossibly small web framework for MicroPython
Affected versions of this package are vulnerable to HTTP Response Splitting in the set_cookie function. An attacker can inject arbitrary HTTP headers by supplying malicious input containing carriage return and line feed sequences, which are then stored in a cookie by the server on behalf of the victim.
Note: This is only exploitable if the attacker has already infiltrated the client, such as through a separate cross-site scripting attack, and can control the data sent to the server for cookie storage.
Workaround
This vulnerability can be mitigated by ensuring that untrusted data is not passed to the set_cookie function.