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Description

Microdot is a minimalistic Python web framework. Prior to 2.6.1, the Response.set_cookie() method does not sanitize its string arguments, and in particular will not detect the presence of the \r\n sequence in them. This can be a potential source of header injection attacks. For a header injection attack through this issue to be possible, an attacker must first infiltrate the client (for example through an independent XSS attack), so that it can send malicious information that is destined to be stored in a cookie by the server on behalf of the victim. An attacker that infiltrates one client can only orchestrate a header injection attack for that client, all other clients that were not infiltrated are safe. This vulnerability is fixed in 2.6.1.

PUBLISHED Reserved 2026-04-30 | Published 2026-05-11 | Updated 2026-05-11 | Assigner GitHub_M




LOW: 3.7CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

Problem types

CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')

Product status

< 2.6.1
affected

References

github.com/...crodot/security/advisories/GHSA-7wc8-wvc4-m498

github.com/...ommit/99b281b45faef8472410f2d56bfef496dfbd95d5

github.com/miguelgrinberg/microdot/blob/main/CHANGES.md

cve.org (CVE-2026-42874)

nvd.nist.gov (CVE-2026-42874)

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