CVE-2025-67500

Mastodon Error Handling Discrepancy Enables Private Status Existence Enumeration

LOW

3.7

CVSS Score

Published: December 9, 2025 at 11:44 PM UTC

Updated: October 14, 2026 at 09:10 PM UTC

2 products affected across 2 vendorsMastodonMastodon

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Severity

LOW3.7

Exploit prediction

EPSS 0.2%

SSVC

No known exploit

Description

Mastodon is a free, open-source social network server based on ActivityPub. Versions 4.2.27 and prior, 4.3.0-beta.1 through 4.3.14, 4.4.0-beta.1 through 4.4.9, 4.5.0-beta.1 through 4.5.2 have discrepancies in error handling which allow checking whether a given status exists by sending a request with a non-English Accept-Language header. Using this behavior, an attacker who knows the identifier of a particular status they are not allowed to see can confirm whether this status exists or not. This cannot be used to learn the contents of the status or any other property besides its existence. This issue is fixed in versions 4.2.28, 4.3.15, 4.4.10 and 4.5.3.

Affected

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

Mastodon · Joinmastodon

95%

v < 4.2.284.3.0 ≤ v < 4.3.154.4.0 ≤ v < 4.4.104.5.0 ≤ v < 4.5.3

Mastodon · Mastodon

90%

v < 4.2.28

Affected range stops below 4.2.28, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.3.15, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.4.10, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.5.3, 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_CONFIRMVendor Advisory

Source: cverecord

https://github.com/mastodon/mastodon/security/advisories/GHSA-gwhw-gcjx-72v8

x_refsource_MISCPatch

Source: cverecord

https://github.com/mastodon/mastodon/pull/37077/commits/9957d3218cb33fea6a44bb285e2ba4795a059e4f

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

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

CVSS

3.7LOWGitHub_M

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

Vector?

Quick Info

StatusANALYZED

CWE

CWE-204

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