CVE-2026-111633
ZKEACMS through 4.4 contains an authentication bypass vulnerability that allows unauthenticated attackers to forge REST API JWT bearer tokens using a hard-coded HMAC-SHA256 signing key in JwtBearerDefaults.cs.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.44%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
ZKEACMS through 4.4 contains an authentication bypass vulnerability that allows unauthenticated attackers to forge REST API JWT bearer tokens using a hard-coded HMAC-SHA256 signing key in JwtBearerDefaults.cs. Attackers can sign a token with the Name claim set to 'admin' to call ApiAuthorize endpoints, modifying articles and products and reading form submissions.
- CVSS 4.0
- 8.8 HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:L/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/M
- EPSS
- 0.44% probability · 38th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-321
- Source
- disclosure@vulncheck.com
EPSS moved from 0.3% on 17 October 2026 to 0.4% on 26 October 2026.
References
- https://github.com/SeriaWei/ZKEACMS/blob/v4.4/src/ZKEACMS/Api/JwtBearerDefaults.cs#L14-L19
- https://github.com/SeriaWei/ZKEACMS/blob/v4.4/src/ZKEACMS/BuilderAuthentication.cs#L41-L52
- https://github.com/SeriaWei/ZKEACMS/issues/531
- https://hackmd.io/@hieuPenguinnn/zkeacms-hardcoded-jwt-signing-key-admin-auth-bypass
- https://www.vulncheck.com/advisories/zkeacms-through-4.4-authentication-bypass-via-hard-coded-jwt-signing-key
- https://github.com/SeriaWei/ZKEACMS/issues/531
- https://hackmd.io/@hieuPenguinnn/zkeacms-hardcoded-jwt-signing-key-admin-auth-bypass
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.