---
id: "CVE-2026-121994"
kind: "vulnerability"
aliases: ["CVE-2026-121994"]
title: "GDB: remote protocol handler overflow lets a debug target run code"
severity: "high"
cvss: 8.8
epss: null
exploited: false
status: "open"
category: "other"
products: [{"name": "gdb", "fixed": [], "affected": "RHEL 6, 7, 8, 9, 10 and Hardened Images (per Red Hat; some streams unaffected)", "ecosystem": "redhat"}]
ecosystems: []
tags: ["debugging", "embedded", "gdb", "other"]
not_affected_if: ["local-debugging-only", "trusted-targets-only"]
published_at: "2026-11-05T17:18:00+00:00"
first_seen_at: "2026-11-05T17:40:03+00:00"
updated_at: "2026-11-05T17:42:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-121994", "first_seen_at": "2026-11-05T17:40:03+00:00"}, {"source": "analyst", "url": "https://access.redhat.com/security/cve/CVE-2026-121994", "first_seen_at": "2026-11-05T17:42:50+00:00", "cites": ["https://access.redhat.com/security/cve/CVE-2026-121994", "https://bugzilla.redhat.com/show_bug.cgi?id=2565676"]}]
exploit_sources: []
---

# GDB: remote protocol handler overflow lets a debug target run code

The GDB debugger's remote protocol handler writes a register reply into a stack buffer without checking its size. A malicious debug target can overflow that buffer and run arbitrary code inside the GDB process.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- redhat:gdb affected RHEL 6, 7, 8, 9, 10 and Hardened Images (per Red Hat; some streams unaffected) fixed no fixed version listed

## How to check

- Run `gdb --version`; Red Hat lists its shipped gdb on RHEL 6, 7, 8, 9, 10 and Hardened Images as affected (some RHEL 8/9/10 streams listed unaffected; upstream version range not published).
- Check whether anyone runs `target remote` / `target extended-remote` to a gdbserver, emulator or board you do not control, and then reads registers (p packet).

## Fix

No fixed release published as of 2026-11-05 (Red Hat Bugzilla 2565676 status NEW). Only connect GDB to trusted debug targets.

## Timeline

- 2026-11-05T17:40:03+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-121994
- 2026-11-05T17:42:50+00:00 analyst https://access.redhat.com/security/cve/CVE-2026-121994 — Read Red Hat CVE page + Bugzilla 2565676 (primary, RH is CNA). No fix released (bug status NEW); RH says no mitigation, only connect to trusted targets. Upstream GDB versions not stated anywhere; no PoC, not exploited.

## Documents

- [advisory] Red Hat CVE-2026-121994 https://access.redhat.com/security/cve/CVE-2026-121994
- [describes] Red Hat Bugzilla 2565676 https://bugzilla.redhat.com/show_bug.cgi?id=2565676

## From the sources

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.

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