CVE-2026-97631

Exploitation

Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.

SSVC decision

Not assessed by CISA

EPSS probability

0.48% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 41.5% of scored records. A rank, not a probability.

NVD base score

9.5 (CVSS v4.0), scored by the NVD independently of the CNA.

NVD CVSS vector

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

NVD analysis status

Deferred. NVD last modified this record on 2026-10-28.

Red Hat severity

Critical. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2026-10-22 16:32Z7 DAYS AGO

Last updated

2026-10-28 16:06Z1 DAY AGO

Reserved

2026-09-24

Assigning CNA

TianoCore

Record state

PUBLISHED

Severity

Critical (CVSS 9.5)

CNA CVSS vector

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

Weaknesses

• CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')Base
• CWE-131Incorrect Calculation of Buffer SizeBase
• CWE-787Out-of-bounds WriteBase

Data version

5.2

Document digest

b93a41e0b99da21f266087e96683a7dcdd58bf3afd65289341f7abdd0bc72619

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