CVE-2026-89320 gose - Authentication Bypass

gose contains a broken authentication caused by HmacShaCryptor.Hash returning a constant MAC regardless of input, letting attackers bypass ciphertext integrity, exploit requires use of AES-CBC-HMAC JWE.

CVSS base score 8.8 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.17% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Authentication Bypass
Impact
Broken Authentication
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/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
Published
23 October 2026
Updated
25 October 2026
Weakness
CWE-354

Vendor fix

Update to the latest version with fixed HmacShaCryptor.Hash implementation.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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