CVE-2026-104874

CVE-2026-104874 · Multidict: Reference leak in CIMultiDict/MultiDict items-view union and subtraction

This page contains facts from public vulnerability sources. Check the original advisory before updating.

Multidict is an implementation of a multidict data structure. From 6.7.0 until 6.9.1, the C extension's items-view reflected union operation, operand | d.items(), in multidict_itemsview_or2_impl and subtraction operation, d.items() - operand, in multidict_itemsview_sub1_impl fail to release new key-identity and value references returned for each operand element. Applications that perform these operations over attacker-influenced sequences can leak two strong references per element, and garbage collection cannot reclaim them, so repeated operations can cause unbounded process memory growth and denial of service. Forward union, intersection, non-tuple operand elements, and pure-Python builds are not affected by this reference leak. This issue is fixed in version 6.9.1.

CVSS 5.3 · Medium · EPSS 0.4% · Fix available

Published

2026-10-02T20:21:50.903Z

Updated

2026-10-05T16:25:56.621Z

Stack: system · python

Check your server →