CVE-2026-27468— Mastodon may allow unconfirmed FASP to make subscriptions

Mastodon may allow unconfirmed FASP to make subscriptions

Mastodon is a free, open-source social network server based on ActivityPub. FASP registration requires manual approval by an administrator. In versions 4.4.0 through 4.4.13 and 4.5.0 through 4.5.6, actions performed by a FASP to subscribe to account/content lifecycle events or to backfill content did not check properly whether the FASP was actually approved. This only affects Mastodon servers that have opted in to testing the experimental FASP feature by setting the environment variable `EXPERIMENTAL_FEATURES` to a value including `fasp`. An attacker can make subscriptions and request content backfill without approval by an administrator. Done once, this leads to minor information leak of URIs that are publicly available anyway. But done several times this is a serious vector for DOS, putting pressure on the sidekiq worker responsible for the `fasp` queue. The fix is included in the 4.4.14 and 4.5.7 releases. Admins that are actively testing the experimental "fasp" feature should update their systems. Servers not using the experimental feature flag `fasp` are not affected.

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授权机制缺失

Mastodon 安全漏洞

Mastodon是Mastodon开源的一款基于ActivityPub的开源社交网络服务器。 Mastodon 4.4.0版本至4.4.13版本和4.5.0版本至4.5.6版本存在安全漏洞，该漏洞源于FASP在订阅账户内容生命周期事件或回填内容时未正确检查是否已获批准，可能导致未经批准的订阅和回填请求，引发拒绝服务攻击。

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