CVE-2026-111367
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.
Does this matter?
Lower severity and a low EPSS score (0.33%). Track it; it rarely justifies an emergency change on its own.
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 4.0
- 6.9 MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/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
- 0.33% probability · 26th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-1394
- Source
- disclosure@vulncheck.com
EPSS moved from 0.3% on 16 October 2026 to 0.3% on 26 October 2026.
References
- https://github.com/aaPanel/BillionMail
- https://github.com/aaPanel/BillionMail/blob/v4.9/core/internal/service/batch_mail/jwt.go#L98-L123
- https://github.com/aaPanel/BillionMail/blob/v4.9/core/manifest/config/config.yaml
- https://hackmd.io/@hieuPenguinnn/billionmail-unsubscribe-subscribe-jwt-deterministic-secret-forgery
- https://www.vulncheck.com/advisories/billionmail-through-4.9-forgeable-jwts-via-default-signing-key
- https://hackmd.io/@hieuPenguinnn/billionmail-unsubscribe-subscribe-jwt-deterministic-secret-forgery
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.