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Vulnerability record · CVE-2026-82876 · published 31 August 2026

CVE-2026-82876: Improper verification of cryptographic signature vulnerability

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.

9.3 CVSS 4.0 Critical EPSS 0.12% · top 98.3% CWE-347 · Improper verification of cryptographic signature Awaiting Analysis
9.3CVSS 4.0 base score
0.12%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
3References
10 Sep 2026Last modified by NVD

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.

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
https://github.com/trulycrisp/psychite
https://trulycrisp.github.io/drivefirmware/phison_s11/
https://www.vulncheck.com/advisories/phison-ps3111-s11-controller-firmware-signature-verification-bypass

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Source: NIST National Vulnerability Database (record CVE-2026-82876), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.