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TI-2026-31080 Aliases CVE-2026-42874GHSA-7wc8-wvc4-m498

Microdot: HTTP response splitting in Response.set_cookie()

Priority LOW 17CWE-113Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
High
Impact type
—
Confidentiality · integrity · availability
None · Low · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00215 12th percentileScored 2026-11-07
Fix Fixed microdot (miguelgrinberg): 2.6.1microdot (PyPI): 2.6.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
miguelgrinbergmicrodotbefore 2.6.12.6.1Patch availableCNA
—microdot (PyPI)before 2.6.12.6.1Patch availableGHSA-7wc8-wvc4-m498
  • microdot Vendormiguelgrinberg Affected before 2.6.1 Fixed in 2.6.1 Patch available CNA
  • microdot (PyPI) Vendor— Affected before 2.6.1 Fixed in 2.6.1 Patch available GHSA-7wc8-wvc4-m498

Remediation

  • Fix · CNA microdot (miguelgrinberg) Fixed in 2.6.1
  • Fix · GHSA-7wc8-wvc4-m498 microdot (PyPI) Fixed in 2.6.1 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-42874
  2. 2026-10-03 Alias added: GHSA-7wc8-wvc4-m498

References

Advisory 1

Other 4

  • TI-2026-36072 python-engineio has unbound thread allocation that can cause denial of service CVSS 3.1HIGH 7.5
  • TI-2026-36078 python-engineio has possible denial of service due to maximum payload size sometimes not being enforced CVSS 3.1HIGH 7.5
  • TI-2026-36073 python-socketio: Binary attachment accumulation can cause denial of service CVSS 3.1HIGH 7.5
  • TI-2026-26780 Flask-HTTPAuth invokes token verification callback when missing or empty token was given by client CVSS 3.1HIGH 8.2
  • TI-2025-38159 Deserialization of untrusted data in miguelgrinberg python-socketio CVSS 3.1MEDIUM 6.4

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences