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9.5
CRITICAL CVSS 4.0
CVE-2026-97631
Pre-boot RCE in EDK II PXE driver
Overview
Description

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.

Details
INFO

Published Date :

Oct. 22, 2026, 5:17 p.m.

Last Modified :

Oct. 30, 2026, 8:17 p.m.

Remotely Exploit :

Yes !

Source :

[email protected]
Impact
Affected Products

The following products are affected by CVE-2026-97631 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Tianocore edk2
: Total Affected Vendor : 1 | Products : 1
Scoring
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 134c704f-9b21-4f2e-91b3-4a467353bcc0
CVSS 4.0 CRITICAL 65518388-201a-4f93-8712-366d21fe8d2c
CVSS 4.0 CRITICAL [email protected]
Solution
Update EDK2 BIOS to patch buffer overflow and out-of-bounds write vulnerabilities.
  • Update EDK2 BIOS to the latest version.
  • Apply vendor-supplied security patches.
  • Sanitize buffer size calculations.
  • Validate all user inputs rigorously.
References
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-97631.

URL Resource
https://github.com/tianocore/edk2/security/advisories/GHSA-99cj-7hg9-mp4m
http://www.openwall.com/lists/oss-security/2026/10/28/4
https://arstechnica.com/security/2026/10/code-execution-flaw-in-uefi-firmware-threatens-most-servers-on-planet-earth/
https://github.com/microsoft/mu_basecore/pull/1989
https://github.com/microsoft/mu_basecore/pull/1990
https://news.ycombinator.com/item?id=50265393
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-97631 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-97631 weaknesses.

CAPEC-8: Buffer Overflow in an API Call Buffer Overflow in an API Call CAPEC-9: Buffer Overflow in Local Command-Line Utilities Buffer Overflow in Local Command-Line Utilities CAPEC-10: Buffer Overflow via Environment Variables Buffer Overflow via Environment Variables CAPEC-14: Client-side Injection-induced Buffer Overflow Client-side Injection-induced Buffer Overflow CAPEC-24: Filter Failure through Buffer Overflow Filter Failure through Buffer Overflow CAPEC-42: MIME Conversion MIME Conversion CAPEC-44: Overflow Binary Resource File Overflow Binary Resource File CAPEC-45: Buffer Overflow via Symbolic Links Buffer Overflow via Symbolic Links CAPEC-46: Overflow Variables and Tags Overflow Variables and Tags CAPEC-47: Buffer Overflow via Parameter Expansion Buffer Overflow via Parameter Expansion CAPEC-67: String Format Overflow in syslog() String Format Overflow in syslog() CAPEC-92: Forced Integer Overflow Forced Integer Overflow CAPEC-100: Overflow Buffers Overflow Buffers CAPEC-47: Buffer Overflow via Parameter Expansion Buffer Overflow via Parameter Expansion CAPEC-100: Overflow Buffers Overflow Buffers

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-97631 vulnerability anywhere in the article.

  • The Hacker News
Critical 16-Year-Old UEFI Flaw Can Run Code Before Secure Boot on Network-Booting Servers

A critical 16-year-old flaw in EDK II, the open-source code that most hardware makers use to build UEFI firmware, can allow an attacker to run code on a machine before its operating system loads, but ... Read more

Published Date: Oct 28, 2026 (2 weeks, 1 day ago)
  • Ars Technica
Code-execution flaw in UEFI firmware threatens most servers on planet Earth

BREAKING THE CHAIN OF TRUST Critical flaw in EDK2 allows attackers to execute code early in the boot process. Credit: Getty Images Defenders across the world face the burden of responding to yet anoth ... Read more

Published Date: Oct 27, 2026 (2 weeks, 1 day ago)

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2026-97631 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Oct. 30, 2026

    Action Type Old Value New Value
    Added SSVC {'id': 'CVE-2026-97631', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-10-30T19:34:29.002368Z'}
  • CVE Modified by af854a3a-2127-422b-91ae-364da2661108

    Oct. 28, 2026

    Action Type Old Value New Value
    Added Reference http://www.openwall.com/lists/oss-security/2026/10/28/4
  • CVE Modified by af854a3a-2127-422b-91ae-364da2661108

    Oct. 28, 2026

    Action Type Old Value New Value
    Added Reference https://arstechnica.com/security/2026/10/code-execution-flaw-in-uefi-firmware-threatens-most-servers-on-planet-earth/
    Added Reference https://github.com/microsoft/mu_basecore/pull/1989
    Added Reference https://github.com/microsoft/mu_basecore/pull/1990
    Added Reference https://news.ycombinator.com/item?id=50265393
  • New CVE Received by [email protected]

    Oct. 22, 2026

    Action Type Old Value New Value
    Added Description 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.
    Added CVSS V4.0 AV:N/AC:L/AT:P/PR:N/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:X/V:X/RE:X/U:X
    Added CWE CWE-787
    Added CWE CWE-120
    Added CWE CWE-131
    Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/97xxx/CVE-2026-97631.json">CVE-2026-97631</a>
    Added Reference https://github.com/tianocore/edk2/security/advisories/GHSA-99cj-7hg9-mp4m
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CVSS
Vulnerability Scoring Details
Base CVSS Score: 9.5
Attack Vector
Attack Complexity
Attack Requirements
Privileges Required
User Interaction
VS Confidentiality
VS Integrity
VS Availability
SS Confidentiality
SS Integrity
SS Availability