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TI-2026-73339 Aliases CVE-2026-103937

Incomplete cleanup in Misskey file uploads enables denial of service

Priority MEDIUM 44CWE-459Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

Misskey from 13.0.0 before 2025.4.1 and from 2025.5.0 before 2026.7.0 is affected. Cleanup processing may not run during file uploads (CWE-459), so a remote attacker without privileges can upload files repeatedly. Repeated uploads can exhaust storage or file descriptors and deny service even when federation is disabled.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

Misskey is an open source, federated social media platform. From 13.0.0 until 2025.4.1 and from 2025.5.0 until 2026.7.0, cleanup processing may not execute during file uploads. Repeated uploads can exhaust storage or file descriptors and deny service regardless of whether federation is enabled. This issue is fixed in version 2026.7.0.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00501 43rd percentileScored 2026-11-07
Fix Fixed misskey (misskey-dev): 2025.4.1, 2026.7.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
misskey-devmisskey12.0.0 – 13.14.2; 2023.9.0-beta.1 to before 2025.4.1; 2025.5.0 to before 2026.7.02025.4.1, 2026.7.0Patch availableCNA
  • misskey Vendormisskey-dev Affected 12.0.0 – 13.14.2; 2023.9.0-beta.1 to before 2025.4.1; 2025.5.0 to before 2026.7.0 Fixed in 2025.4.1, 2026.7.0 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:misskey:misskey:*:*:*:*:*:*:*:*——misskey-dev
  • cpe:2.3:a:misskey:misskey:*:*:*:*:*:*:*:* Versions — — ·misskey-dev

Remediation

Upgrade Misskey to version 2026.7.0, which fixes this issue.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

  • Fix · CNA misskey (misskey-dev) Fixed in 2025.4.1, 2026.7.0

Timeline

  1. 2026-10-13 Threatist record created from CVE-2026-103937
  2. 2026-10-14 CISA SSVC decision points changed

References

Other 4

  • TI-2025-18599 Misskey CSRF vulnerability due to insecure configuration of authentication cookie attributes CVSS 3.1HIGH 8.2
  • TI-2025-29081 Misskey CSS Style Injection Vulnerability In `MkUrlPreview` CVSS 3.1HIGH 7.2
  • TI-2025-40906 Misskey has a login rate limit bypass via spoofed X-Forwarded-For header CVSS 4.0MEDIUM 6.9
  • TI-2025-29276 Misskey Directory Traversal Vulnerability in AiScript via `Mk:api` CVSS 3.1HIGH 7.5
  • TI-2025-40839 misskey.js's export data contains private post data CVSS 4.0HIGH 7.1
  • TI-2025-29271 @misskey-dev/summaly Redirect Filter Bypass CVSS 4.0LOW 2.1
See all 38 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences