Is there a public exploit for CVE-2026-121458?

No public exploit for CVE-2026-121458 was found in Exploit-DB, Metasploit, Nuclei templates or public proof-of-concept repositories. That is an absence of evidence rather than proof that none exists.

How severe is CVE-2026-121458?

CVE-2026-121458 scores CVSS 7.1 (v4.0), rated high.

What does CVE-2026-121458 affect?

CVE-2026-121458 affects CoreBunch Instatic.

7.1 High

Instatic before 0.0.21 contains a missing authorization vulnerability in its AI/MCP content read tools that allows low-privileged…

CVE-2026-121458

Instatic before 0.0.21 contains a missing authorization vulnerability in its AI/MCP content read tools that allows low-privileged authenticated users with ai.chat and content.edit.own capabilities to access data rows belonging to other users by calling contentgetdocument and contentlistdocuments without the object-level authorization checks enforced by the normal HTTP API. Attackers can use the MCP interface to retrieve private or unpublished draft content and enumerate rows from the posts system table, resulting in cross-user data disclosure.

Assessment

CVSS: 7.1 (v4.0)
Severity: High
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 3 November 2026
Last updated: 3 November 2026
Affected: CoreBunch · Instatic
Assigner: VulnCheck

CVSS vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

At the source

EUVD (ENISA)

References

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