CVE-2026-50129Public exploitNetwork attack vectorHinoki check available

Anonymous service interruption via unchecked encoding attribute

Published Jun 24, 2026 · Updated Jun 24, 2026

Uncaught exception handling in affected Mastodon releases allows remote attackers to interrupt server or targeted-user services via federated content. MATH_TRANSFORMER calls .value on a missing annotation encoding attribute, raising a NoMethodError that escapes the formatting path. Remote attackers need no account on the target; a stored poisoned status repeatedly breaks timelines, RSS feeds, and moderation views with HTTP 500 responses.

CVSS severity7.5
High
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Uncaught exception handling in affected Mastodon releases allows remote attackers to interrupt server or targeted-user services via federated content. MATH_TRANSFORMER calls .value on a missing annotation encoding attribute, raising a NoMethodError that escapes the formatting path. Remote attackers need no account on the target; a stored poisoned status repeatedly breaks timelines, RSS feeds, and moderation views with HTTP 500 responses.

The record

CVE
CVE-2026-50129
Published
Jun 24, 2026
Updated
Jun 24, 2026
Vendor
Mastodon
Product
Mastodon
Classifications
CWE-248, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.3.24
  2. Affected versionversion=>= 4.4.0-beta.1, < 4.4.18
  3. Affected versionversion=>= 4.5.0-beta.1, < 4.5.11

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mastodon · Mastodonversion=< 4.3.24; version=>= 4.4.0-beta.1, < 4.4.18; version=>= 4.5.0-beta.1, < 4.5.11

Published CVSS scores

7.5GitHub CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-248Uncaught Exception
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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