Disclosure summary
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.
Source-reported weakness categories
CWE-401
Source-specific records & product guidance
Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.
GitHub Reviewed Security Advisories · GHSA-54p9-h82j-f925
Open original source · Updated Oct 05, 2026
Multidict: Reference leak in CIMultiDict/MultiDict items-view union and subtraction
Source severity: MEDIUM / 0
| Ecosystem | Package | Affected range | First patched |
|---|---|---|---|
| pip | multidict | >= 6.7.0, | 6.9.1 |
NIST National Vulnerability Database · NVD-CVE-2026-104874
Open original source · Updated Oct 05, 2026
Only CPE matches marked vulnerable=true are indexed. AND/OR platform conditions must be checked in the original NVD record.
Original records & references
PUBLISHED 2026-10-02T17:16:54-04:00
MODIFIED 2026-10-05T13:17:10-04:00
INGESTED 2026-10-06T11:45:30-04:00