Multidict: Reference leak in CIMultiDict/MultiDict items-view union and subtraction

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-104874
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-02 21:16:54 UTC
Updated2026-10-02 21:16:54 UTC
DescriptionMultidict 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.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

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

Problem Types: CWE-401 | CWE-401 CWE-401: Missing Release of Memory after Effective Lifetime

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
3.1CNADECLARED5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Aio-libs Multidict affected >= 6.7.0, < 6.9.1 Not specified

References

ReferenceSourceLinkTags
github.com/aio-libs/multidict/releases/tag/v6.9.1 [email protected] github.com
github.com/aio-libs/multidict/security/advisories/GHSA-54p9-h82j-f925 [email protected] github.com
github.com/aio-libs/multidict/commit/350b4a07bf8ff851b6d7544e81b1c748bdc... [email protected] github.com
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