CVE-2026-104874

MEDIUMPre-NVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3% (20th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this week
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 5.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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 v3
5.3
EG Score
5.3MEDIUMmedium confidence
EG Risk
28
EG Risk 28/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity53% × 45%
Exploitation0% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track or Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.3%
EPSS %ILE
20th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track or Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

October 2, 2026

Last Modified

October 2, 2026

Advisory Details (2)

Auto-updated Oct 2, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit.
github_commit

commit 350b4a07bf8f (aio-libs/multidict)

Fix landed in aio-libs/multidict commit 350b4a07bf8f — awaiting tagged release

https://github.com/aio-libs/multidict/commit/350b4a07bf8ff851b6d7544e81b1c748bdc74c40
github Patch Available🟡 PoC Available

Reference leak in CIMultiDict/MultiDict items-view union and subtraction · Advisory · aio-libs/multidict · GitHub

https://github.com/aio-libs/multidict/security/advisories/GHSA-54p9-h82j-f925

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 6× in last 7d / 6× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-10-04 23:21 UTCEPSS rescore
  2. 2026-10-03 20:00 UTCEG score recompute
  3. 2026-10-03 14:25 UTCEPSS rescore
  4. 2026-10-02 21:22 UTCEG score recompute
  5. 2026-10-02 20:28 UTCEG score recompute
  6. 2026-10-02 20:25 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-104874?
CVE-2026-104874 is a medium vulnerability published on October 2, 2026. 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 multidictitemsviewor2impl and subtraction operation, d.items() - operand, in multidictitemsviewsub1impl fail to release new…
When was CVE-2026-104874 disclosed?
CVE-2026-104874 was first published on October 2, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-104874 actively exploited?
CVE-2026-104874 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (20th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-104874?
CVE-2026-104874 has a CVSS base score of 5.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-104874?
A fix for CVE-2026-104874 is available: update to the fixed version the vendor names in its advisory.

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