{"cve":"CVE-2026-104874","nvd":{"published":"2026-10-02T21:16:54.993","modified":"2026-10-06T16:08:43.180","status":"Deferred","description":"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_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","score":5.3},"cwes":["CWE-401"],"references":["https://github.com/aio-libs/multidict/commit/350b4a07bf8ff851b6d7544e81b1c748bdc74c40","https://github.com/aio-libs/multidict/releases/tag/v6.9.1","https://github.com/aio-libs/multidict/security/advisories/GHSA-54p9-h82j-f925","https://github.com/aio-libs/multidict/security/advisories/GHSA-54p9-h82j-f925"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:57:46.668721662+00:00"},"epss":{"cve":"CVE-2026-104874","score":0.00448,"percentile":0.38682,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-54p9-h82j-f925","url":"https://osv.dev/vulnerability/GHSA-54p9-h82j-f925","summary":"Multidict: Reference leak in CIMultiDict/MultiDict items-view union and subtraction","modified":"2026-10-15T14:56:05.601333622Z","packages":[{"ecosystem":"PyPI","name":"multidict","purl":"pkg:pypi/multidict","ranges":[">=6.7.0 <6.9.1"],"fixed":["6.9.1"]}]},{"id":"PYSEC-2026-4244","url":"https://osv.dev/vulnerability/PYSEC-2026-4244","summary":"Multidict: Reference leak in CIMultiDict/MultiDict items-view union and subtraction","modified":"2026-10-15T14:45:08.892406163Z","packages":[{"ecosystem":"PyPI","name":"multidict","purl":"pkg:pypi/multidict","ranges":[">=6.7.0 <6.9.1"],"fixed":["6.9.1"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}