CVE Catalog

CVE-2026-104874

MediumCVSS 5.3
Published: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.30%

20th percentile - higher than 20% of all known CVEs

Summary

Multidict is an implementation of a multidict data structure. From 6.7.0 until 6.9.1, the C extension's items-view union and subtraction operations fail to release new key-identity and value references for each operand element, leaking two strong references per element. Applications performing these operations over attacker-influenced sequences can experience unbounded memory growth and denial of service.

Risk Assessment

Repeated operations can lead to memory exhaustion and denial of service (DoS) in applications processing attacker-controlled input.

Recommendation

Update the multidict library to version 6.9.1 or later, which fixes the reference leak.

Related vulnerabilities

Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS