CVE-2026-104874
MEDIUMDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Exploit Intelligence
Low risk: more likely to be exploited than 39% of all known CVEs.
References
Related Vulnerabilities
Other CWE-401 (Missing Release of Memory (Memory Leak)) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2020-13934 | High | 7.5 | 64% | - | Fix |
| CVE-2016-6304 | High | 7.5 | 63% | - | Fix |
| CVE-2019-12265 | Medium | 5.3 | 60% | - | Fix |
| CVE-2001-0136 | Medium | 5.0 | 45% | - | - |
| CVE-2016-4232 | High | 7.5 | 36% | - | - |
| CVE-2001-0543 | Medium | 5.0 | 19% | - | - |
Common questions
How do I fix CVE-2026-104874?
Upgrade multidict to 6.9.1 or later.
Is CVE-2026-104874 being actively exploited?
Not that we know of. CVE-2026-104874 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.45% is the estimated probability that it will be exploited in the next 30 days. That is higher than 39% of all scored CVEs.
How severe is CVE-2026-104874?
CVE-2026-104874 has a CVSS v3 base score of 5.3, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-104874 affect?
Published advisories record a fix for multidict (PyPI (Python)). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-10-06.