# CVE-2026-97631: EDK2 buffer overflow in PXE driver pre-boot RCE

Source: https://junglewise.ai/threats/cve-2026-97631-edk2-contains-a-vulnerability-in-bios-where-a-user-may-cause-out  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-22. Updated: 2026-10-22  
License: CC BY 4.0 with a link back

CVE-2026-97631 · Severity: info · Published 2026-10-22

EDK2 is the open-source firmware used in many computers during the boot process. An attacker on a network can send malicious network messages to a computer while it is starting up and loading an operating system, causing the firmware to execute arbitrary code before any operating system protection is active. This gives the attacker complete control over the system before the OS even loads.

Technologies: [Tianocore Edk2](https://junglewise.ai/threats/technologies/edk2). Vendors: [Tianocore](https://junglewise.ai/threats/vendors/tianocore).

## Quick answers

**Is CVE-2026-97631 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-97631 being exploited in the wild.

**How severe is CVE-2026-97631?** Informational severity, published 22 October 2026.

**Which products and versions are affected?** Tianocore Edk2 master as of 2026-09-14.

**Is there a fix for CVE-2026-97631?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-97631 attacked?** It is attacked over the network, in device firmware.

**Am I affected by CVE-2026-97631?** Check whether you run Tianocore Edk2 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A buffer overflow exists in the EDK2 PXE Base Code driver (NetworkPkg/UefiPxeBcDxe) in both IPv4 and IPv6 ICMP error handlers. The vulnerability is triggered by incorrect bounds checking when copying ICMP error messages into a fixed 504-byte field; an oversized message causes out-of-bounds writes past the intended buffer. An unauthenticated remote attacker can deliver a unicast ICMP error message during the PXE boot window to corrupt DXE-phase memory and achieve arbitrary code execution at ring 0, before Secure Boot verification or OS load.

## Affected products

- TianoCore EDK2 master as of 2026-09-14

## Timeline

- 2026-10-22: disclosed
- 2026-09-14: other: vulnerability present in master branch as of this date

## References

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

## Related threats

- [EDK2 SMRAM information disclosure during transient execution](https://junglewise.ai/threats/cve-2026-18448-edk2-contains-a-vulnerability-in-bios-where-a-privileged-attacker)
- [EDK2 MmSaveStateLib out-of-bounds write in AMD SysCall path](https://junglewise.ai/threats/cve-2026-14968-edk2-contains-vulnerabilities-in-bios-where-skilled-and)
- [The Ubuntu edk2 UEFI firmware packages accidentally allowed the UEFI Shell to be accessed in Secure Boot environments…](https://junglewise.ai/threats/cve-2025-2486-the-ubuntu-edk2-uefi-firmware-packages-accidentally-allowed-the)