CVE-2026-25540— Mastodon's signature-dependent ActivityPub collection responses cached under signature-independent keys (Web Cache Poisoning via `Rails.cache`)
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I. Basic Information for CVE-2026-25540
Vulnerability Information
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Vulnerability Title
Mastodon's signature-dependent ActivityPub collection responses cached under signature-independent keys (Web Cache Poisoning via `Rails.cache`)
Source: NVD (National Vulnerability Database)
Vulnerability Description
Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.3.19, 4.4.13, 4.5.6, Mastodon is vulnerable to web cache poisoning via `Rails.cache. When AUTHORIZED_FETCH is enabled, the ActivityPub endpoints for pinned posts and featured hashtags have contents that depend on the account that signed the HTTP request. However, these contents are stored in an internal cache and reused with no regards to the signing actor. As a result, an empty response generated for a blocked user account may be served to requests from legitimate non-blocked actors, or conversely, content intended for non-blocked actors may be returned to blocked actors. This issue has been patched in versions 4.3.19, 4.4.13, 4.5.6.
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
Source: NVD (National Vulnerability Database)
Vulnerability Type
通过缓存导致的信息暴露
Source: NVD (National Vulnerability Database)
Vulnerability Title
Mastodon 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Mastodon是Mastodon开源的一款基于ActivityPub的开源社交网络服务器。 Mastodon 4.3.19之前版本、4.4.13之前版本和4.5.6之前版本存在安全漏洞，该漏洞源于Web缓存投毒，可能导致缓存内容被错误复用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2026-25540
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IV. Related Vulnerabilities
Same product: mastodon
- CVE-2026-41259
Mastodon: Insufficient verification of email addresses - CVE-2026-33869
Mastodon has a denial of service for quote authorization - CVE-2026-33868
Mastodon has a GET-Based Open Redirect via '/web/%2F<domain> - CVE-2026-27477
Mastodon has SSRF via unvalidated FASP Provider base_url - CVE-2026-27468
Mastodon may allow unconfirmed FASP to make subscriptions
Same vendor: mastodon
- CVE-2026-41259
Mastodon: Insufficient verification of email addresses - CVE-2026-33869
Mastodon has a denial of service for quote authorization - CVE-2026-33868
Mastodon has a GET-Based Open Redirect via '/web/%2F<domain> - CVE-2026-27477
Mastodon has SSRF via unvalidated FASP Provider base_url - CVE-2026-27468
Mastodon may allow unconfirmed FASP to make subscriptions
Same weakness: CWE-524
- CVE-2026-6907
Potential exposure of private data due to incorrect handling - CVE-2026-22741
Static resource cache poisoning in Spring MVC and WebFlux - CVE-2025-14806
IBM Planning Analytics Information Disclosure - CVE-2026-27205
Flask session does not add `Vary: Cookie` header when access - CVE-2026-24472
Hono cache middleware ignores "Cache-Control: private" leadi
V. Comments for CVE-2026-25540
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