SB2026042387 - Use of cache containing sensitive information in Mastodon

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Main Vulnerability Database SB2026042387

SB2026042387 - Use of cache containing sensitive information in Mastodon

Published: April 23, 2026

Security Bulletin ID SB2026042387
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Information disclosure

Breakdown by Severity

Medium 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Use of cache containing sensitive information (CVE-ID: CVE-2026-25540)

CWE-ID: CWE-524 - Use of Cache Containing Sensitive Information

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Green


The vulnerability allows a remote attacker to disclose sensitive information and cause a denial of service.

The vulnerability exists due to use of a cache containing sensitive information in the ActivityPub endpoints for pinned posts and featured hashtags when handling signed HTTP requests with AUTHORIZED_FETCH enabled. A remote attacker can send crafted requests that manipulate cache state to disclose sensitive information and cause a denial of service.

This only occurs when AUTHORIZED_FETCH is enabled and the target user has blocked the actor or their server. Cached responses may be reused for up to 3 minutes across different signing actors.


Remediation

Install update from vendor's website.

References