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Fencer Intel
high 7.3

CVE-2026-90579 json

cheshire-cat-ai Cheshire Cat AI custom_auth_handler.py _authorize_http_key missing authentication

published last mo. modified last mo. also EUVD-2026-77064

cvss
7.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 51%
public exploits
0
none known

Summary

A vulnerability has been found in cheshire-cat-ai Cheshire Cat AI up to 1.9.2. This affects the function _authorize_http_key of the file core/cat/factory/custom_auth_handler.py. The manipulation of the argument user_id leads to missing authentication. The attack may be initiated remotely. The exploit has been disclosed to the public and may be used. The project was informed of the problem early through an issue report but has not responded yet.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
last mo.

Exploit prediction

0.65% chance of exploitation in the next 30 days, higher than 51% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/cheshire-cat-ai/core/issues/1137 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
CNA 3.1 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:X/RC:R
CNA 3.0 7.3 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:X/RC:R
CNA 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P/E:POC/RL:ND/RC:UR
CNA 4.0 5.5 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CNA 3.1 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
CNA 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Inferred packages

No advisory lists a package for this vulnerability yet. The CVE names these as products and links their GitHub repository, and the package registry names the same repository, so they are probably the affected packages. Low confidence: the versions are the CVE’s own for the product, and a stack check reports the package as unchecked when there are none.

ecosystem package repository affected
pypi cheshire-cat-ai cheshire-cat-ai/core no versions given

Affected products

  • cheshire-cat-ai Cheshire Cat AI

Classification

Weakness
  • CWE-306 Missing Authentication for Critical Functionality
  • CWE-287 Improper Authentication

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.