CVE-2026-48115

Misskey: Improper Authorization in the Announcements API

Published Aug 3, 2026 CVSS 4.0 · 6.3 Medium EPSS < 1% KEV · Not listed

Description

Misskey is an open source, federated social media platform. All Misskey servers running versions 2024.5.0 and later, but prior to 2026.5.4, contain a vulnerability in the Server Announcements API where insufficient permission checks allow attackers to access limited portions of data that they normally couldn't view. This vulnerability occurs whether or not federation is enabled. This issue has been fixed in version 2026.5.4.

Analysis

Technical impact

An improper authorization flaw in Misskey’s Server Announcements API permits attackers to retrieve sensitive announcement data that they normally cannot access, exposing personal or private information. The vulnerability stems from missing permission checks in the API (CWE‑285) and can lead to data leakage without affecting the integrity or availability of the platform.

Affected Systems

All Misskey servers with versions from 2024.5.0 up to, but not including, 2026.5.4 are vulnerable. The issue is present regardless of whether federation is enabled, affecting every instance that has not been updated to 2026.5.4 or newer.

Risk and Exploitability

The CVSS score of 6.3 indicates a moderate to high severity, and while the EPSS score is currently unavailable, the vulnerability is not listed in CISA’s KEV catalog. Attackers can exploit the flaw by making API calls to the announcements endpoint, potentially accessing data beyond their authorization level. The lack of noted active exploitation suggests the exploit vector is available but not yet widely leveraged.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

misskey-dev

misskey

affected

Version	Status	Constraints
`>= 2024.5.0, < 2026.5.4`	affected	—

No data.

Vendor Product Versions

Misskey

Version	Status	Scheme	Platform
`[2024.5.0,2026.5.4)`	affected	semver	—

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Update to Misskey version 2026.5.4 or newer
If immediate update is not possible, temporarily disable the announcements API or limit its usage to strictly authenticated users
As a workaround, enforce explicit permission checks in the API code before returning announcement data

Generated by OpenCVE AI on August 4, 2026 at 09:40 UTC.

Tracking

Advisories

No advisories available

Metrics

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements Present

User Interaction None

Vulnerable System Confidentiality Impact Low

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.421% probability within 30 days)

Exploitation none

Automatable no

Technical Impact partial

References

Link	Providers
https://github.com/misskey-dev/misskey/releases/tag/2026.5.4
https://github.com/misskey-dev/misskey/security/advisories/GHSA-j49q-76hx-mv8f

History

Aug 5, 2026 3:30 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Aug 5, 2026 10:00 AM First appearance in the feed. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Misskey Misskey misskey
Vendors & Products		Misskey Misskey misskey

Aug 3, 2026 9:45 PM Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Description		Misskey is an open source, federated social media platform. All Misskey servers running versions 2024.5.0 and later, but prior to 2026.5.4, contain a vulnerability in the Server Announcements API where insufficient permission checks allow attackers to access limited portions of data that they normally couldn't view. This vulnerability occurs whether or not federation is enabled. This issue has been fixed in version 2026.5.4.
Title		Misskey: Improper Authorization in the Announcements API
Weaknesses		CWE-285
References		https://github.com/misskey-dev/misskey/releases/tag/2026.5.4 https://github.com/misskey-dev/misskey/security/advisories/GHSA-j49q-76hx-mv8f
Metrics		cvssV4_0 `{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N'}`