CVE-2025-27157

Mastodon's rate-limits are missing on `/auth/setup`

MEDIUM

5.3

CVSS Score

Published: February 27, 2025 at 05:12 PM UTC

Updated: June 17, 2026 at 09:03 AM UTC

2 products affected across 2 vendorsMastodonMastodon

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Severity

MEDIUM5.3

Exploit prediction

EPSS 0.4%

SSVC

No known exploit

Description

Mastodon is a self-hosted, federated microblogging platform. Starting in version 4.2.0 and prior to versions 4.2.16 and 4.3.4, the rate limits are missing on `/auth/setup`. Without those rate limits, an attacker can craft requests that will send an email to an arbitrary addresses. Versions 4.2.16 and 4.3.4 fix the issue.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Mastodon · Joinmastodon

95%

4.2.0 ≤ v < 4.2.164.3.0 ≤ v < 4.3.4

Affected range stops below 4.2.16, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.3.4, so it looks safe — our inference, not a vendor statement

Mastodon · Mastodon

60%

v < 4.2.16v < 4.3.4

Affected range stops below 4.2.16, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.3.4, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (2)

x_refsource_MISCPatch

Source: [email protected]

https://github.com/mastodon/mastodon/commit/06f879ce9bea195344ac9f71e6799eea500628ec

x_refsource_CONFIRMVendor Advisory

Source: [email protected]

https://github.com/mastodon/mastodon/security/advisories/GHSA-v39f-c9jj-8w7h

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.3MEDIUMGitHub_M

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: LOW

Vector?

Quick Info

StatusANALYZED

CWE

CWE-770

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