9.5 Critical

EDK2 contains a vulnerability in BIOS where a user may cause “Out-of-bounds Write”, Classic Buffer Overflow, and “Incorrect Calculation of…

CVE-2026-97631

EDK2 contains a vulnerability in BIOS where a user may cause “Out-of-bounds Write”, Classic Buffer Overflow, and “Incorrect Calculation of Buffer Size” by remote access. Successful exploitation of this vulnerability can lead to arbitrary code execution. It could also impact Confidentiality, Integrity, and Availability.

Proof-of-concept code is published

Public PoC

Public PoCslabbdev/uefi-pxe-cve-2026-976311 stars
Public PoCTry2Take/CVE-2026-97631-PoC1 stars
Public PoCRayanZiani/Bootjack

Signals come from Exploit-DB, Metasploit, Nuclei and published proof-of-concept repositories. Their absence means nothing was found, not that nothing exists.

Assessment

CVSS: 9.5 (v4.0)
Severity: Critical
EPSS: 0.64% chance of exploitation in the next 30 days
Known exploited: Not listed in CISA KEV
Exploit availability: Public PoC
Published: 22 October 2026
Last updated: 30 October 2026
Affected: Tianocore
Assigner: TianoCore

CVSS vectorCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

At the source

EUVD (ENISA)

References

https://github.com/tianocore/edk2/security/advisories/GHSA-99cj-7hg9-mp4m

Community proofs of concept

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