CVE Intelligence
Critical Memory corruption

CVE-2026-97631 — Pre-boot RCE in EDK II PXE driver

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.

Published Oct 22, 2026 · Updated Oct 28, 2026 · Sources: CVE Program (cve.org) e CISA ADP, NIST National Vulnerability Database · CNA: TianoCore

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.5% (30-day exploitation probability)+6
  • Technical severity (critical)+10

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.48%
ahead of 42% of scored CVEs · Oct 28, 2026
Affects
Tianocore
Edk2
CVSS base
9.5
Critical · 2 source(s)

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Tianocore Edk2).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  4. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Tianocore Edk2 ≤ edk2-stable202608 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Attack requirements
Present
Privileges required
None
User interaction
None
Scope
X
Confidentiality (vulnerable system)
High
Integrity (vulnerable system)
High
Availability (vulnerable system)
High
Confidentiality (subsequent)
High
Integrity (subsequent)
High
Availability (subsequent)
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
9.5 CVSS 4.0 Critical — — infosec@edk2.groups.io via NIST National Vulnerability Database
9.5 CVSS 4.0 Critical — — TianoCore via CVE Program (cve.org) e CISA ADP
CVSS:4.0/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 (score shown at the top: infosec@edk2.groups.io)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-120 · Classic Buffer Overflow

Other CVEs with this weakness →

EPSS over time FIRST

Oct 23, 2026 → Oct 28, 2026 · 6 reading(s) · max 0.48%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
web/proxy/WAF logsnetwork IDS/IPSendpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • Source status changed · Published → Deferred
    Oct 22, 2026 · NIST National Vulnerability Database
  • Record published
    Oct 22, 2026
  • CVSS changed · 9.5
    Oct 22, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · → Published
    Oct 22, 2026 · CVE Program (cve.org) e CISA ADP
  • Record created in this database
    Oct 22, 2026 · CVE Program (cve.org) e CISA ADP
  • CVE published
    Oct 22, 2026 · TianoCore

Source activity

Repeated readings are counted rather than listed.

  • 2× References added · Oct 28, 2026 – Oct 28, 2026
  • 1× Official description updated · Oct 22, 2026 – Oct 22, 2026

References

6 on the record

Elsewhere on this site

Tianocore
every CVE for this vendor
Memory corruption
same class
CWE-120
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-111497 Google Brotli Unchecked Return Value Vulnerability KEV 6d
  • CVE-2025-2296 Un-verified kernel bypass Secure Boot mechanism in direct boot mode Dec 9, 2025
  • CVE-2024-38798 Uncleared password keystrokes in circular queue can lead to information disclosure or escalation of privilege Dec 9, 2025
  • CVE-2025-2486 UEFI Shell accessible in AAVMF with Secure Boot enabled on Ubuntu Nov 26, 2025
  • CVE-2023-48733 An insecure default to allow UEFI Shell in EDK2 was left enabled in Ubuntu's EDK2. This allows an... Feb 14, 2024

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No CISA SSVC assessment.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-97631 is "Pre-boot RCE in EDK II PXE driver", rated Critical. It affects Edk2 (Tianocore); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.5 describes technical severity. EPSS 0.48% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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