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VulnerabilityPublished

CVE-2026-14541: Google mcp-toolbox · (Improper Authentication)

Affects Google mcp-toolboxSource CVE Database V5

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Not known to be exploited · CVSS 8.0 High.

Data as of 29 Oct 2026, 07:15 UTC

CVSS 4.0 base score
8.0High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 16% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 31 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Googlemcp-toolboxAffected
  • =1.4.0
Fixed in–

AI-suggested

Until a fix is available, ensure that the Google OAuth provider component is configured with an explicit audience or clientId when mcpEnabled is true to enforce proper token audience validation.

Description

CVE-2026-14541 is an authentication bypass vulnerability in Google mcp-toolbox version 1.4.0. The flaw occurs when the Google OAuth provider component is initialized with mcpEnabled set to true but without an explicitly defined audience or clientId. This causes the ValidateMCPAuth pipeline to skip audience validation for opaque tokens, allowing acceptance of any valid Google OAuth access token, even those intended for unrelated applications. This can grant unauthorized access to protected tools and data backends.

References

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