Live › incident › INC-anthropic-t33dncr5ydvl

highVendorresolved

Anthropic: Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1

Not triaged yet. The sources’ own description is below.

Known so far

1/6

high

no CVSS yet; severity from the sources

known so far1 of 6

missing: versions, how to check, fix, exploitation, summary

First public: Sep 11, 2026 UTC
Last modified: Sep 11, 2026
Status: resolved
Known exploitation: None reported
Public exploit: None on GitHub
EPSS: not scored

First seen by InfraStack 2026-10-23 19:12 UTC. All times on this page are UTC.

Who is affected

1 product

Product	Ecosystem	Affected	Fixed in
Anthropic	vendor	–	–

Who cares: ai, anthropic, incident, llm, ops
Not affected if: –

How to check

Unknown from the sources.

The fix

Unknown from the sources.

Who had it, and when

1 source

status page2026-10-23 19:12 UTC · published 2026-09-11 14:19 UTC · anthropic:t33dncr5ydvl

Each row is the first time that source carried this signal. The analyst’s rows are its own findings.

Know the next one before it finds you.

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highVendorresolved

Anthropic: Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1

Not triaged yet. The sources’ own description is below.

Known so far

1/6

high

no CVSS yet; severity from the sources

known so far1 of 6

missing: versions, how to check, fix, exploitation, summary

First public: Sep 11, 2026 UTC
Last modified: Sep 11, 2026
Status: resolved
Known exploitation: None reported
Public exploit: None on GitHub
EPSS: not scored

First seen by InfraStack 2026-10-23 19:12 UTC. All times on this page are UTC.

Who is affected

1 product

Product	Ecosystem	Affected	Fixed in
Anthropic	vendor	–	–

Who cares: ai, anthropic, incident, llm, ops
Not affected if: –

How to check

Unknown from the sources.

The fix

Unknown from the sources.

Who had it, and when

1 source

status page2026-10-23 19:12 UTC · published 2026-09-11 14:19 UTC · anthropic:t33dncr5ydvl

Each row is the first time that source carried this signal. The analyst’s rows are its own findings.

Know the next one before it finds you.

Add to Slack

Anthropic: Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1

Who is affected

How to check

The fix

Who had it, and when

Know the next one before it finds you.

Anthropic: Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1

Who is affected

How to check

The fix

Who had it, and when

Know the next one before it finds you.

What the sources say, verbatim

Sources