---
id: CVE-2026-121994
title: >-
  Gdb: gdb: stack buffer overflow in fetch_register_using_p via unchecked
  p-reply length
summary: >-
  A stack buffer overflow in the GDB client's remote protocol handler allows an
  attacker-controlled debug target to execute arbitrary code in the GDB process.
  The vulnerability exists in fetch_register_using_p, which decodes a stub's
  regis…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-121
vendor: Red Hat
product: crash
affected:
  - crash
  - gdb (all versions)
  - gdb (all versions)
  - gdb (all versions)
  - crash
  - gcc-toolset-14-gdb (all versions)
  - gcc-toolset-15-gdb (all versions)
  - gdb (all versions)
  - crash
  - gdb (all versions)
  - gdb (all versions)
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-11-05T17:25:53.959151Z'
published: '2026-11-05'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T19:02:19.809Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-121994'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-121994'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2565676'
    label: RHBZ#2565676
tags:
  - cve.org
ingestedAt: '2026-11-05T22:38:31.494Z'
---

## Overview

A stack buffer overflow in the GDB client's remote protocol handler allows an attacker-controlled debug target to execute arbitrary code in the GDB process. The vulnerability exists in fetch_register_using_p, which decodes a stub's register reply into an alloca-sized buffer without bounding writes by the register width.

## Affected

- `crash`
- `gdb (all versions)`
- `gdb (all versions)`
- `gdb (all versions)`
- `crash`
- `gcc-toolset-14-gdb (all versions)`
- `gcc-toolset-15-gdb (all versions)`
- `gdb (all versions)`
- `crash`
- `gdb (all versions)`
- `gdb (all versions)`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

### Workarounds

There is no mitigation for this vulnerability. Users should only connect GDB to trusted debug targets.