Medium severity · published Oct 15, 2026
CVE-2026-111367
BillionMail through 4.9 Forgeable JWTs via Default Signing Key
6.5
CVSS
0.3%
EPSS
No
On KEV
Description
BillionMail through 4.9 contains a hard-coded cryptographic key vulnerability that allows unauthenticated attackers to forge unsubscribe and subscribe-confirm JWTs by computing the key from shipped configuration constants. Attackers can submit forged tokens to /api/unsubscribe, /api/unsubscribe_new, or /api/subscribe/confirm to deactivate any contact or force confirmed subscriptions.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
Low
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 26% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
BI
BillionMail · aaPanel
through 4.9 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-111367
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-111367
github.com
https://github.com/aaPanel/BillionMail
github.com
https://github.com/aaPanel/BillionMail/blob/v4.9/core/internal/service/batch_mail/jwt.go#L98-L123
github.com
https://github.com/aaPanel/BillionMail/blob/v4.9/core/manifest/config/config.yaml
hackmd.io
https://hackmd.io/@hieuPenguinnn/billionmail-unsubscribe-subscribe-jwt-deterministic-secret-forgery
www.vulncheck.com
https://www.vulncheck.com/advisories/billionmail-through-4.9-forgeable-jwts-via-default-signing-key