CVE-2026-42874
Microdot has HTTP response splitting in Response.set_cookie()
Description
### Impact 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. ### Patches Upgrade to version 2.6.1. ### Workarounds Do not pass untrusted data to the `Response.set_cookie()` method.
How to fix CVE-2026-42874
To remediate CVE-2026-42874, upgrade the affected package to a fixed version below.
- —upgrade to 2.6.1 or later
Is CVE-2026-42874 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 2.6.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | LOW3.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N |