---
id: CVE-2026-121996
title: >-
  Gdb: gdbserver: heap disclosure and wild pointer in gdb_parse_agent_expr via
  untrusted agent-expression length
summary: >-
  A length validation flaw in gdbserver's agent-expression parser allows an
  unauthenticated remote attacker to read uninitialized heap memory from the
  gdbserver process and cause a denial of service. Disclosed heap content
  includes address…
severity: high
cvss: 8.2
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-822
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: 'yes'
  technicalImpact: partial
  timestamp: '2026-11-05T18:52:10.802560Z'
published: '2026-11-05'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T18:52:23.924Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-121996'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-121996'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2565678'
    label: RHBZ#2565678
tags:
  - cve.org
ingestedAt: '2026-11-05T22:38:31.482Z'
---

## Overview

A length validation flaw in gdbserver's agent-expression parser allows an unauthenticated remote attacker to read uninitialized heap memory from the gdbserver process and cause a denial of service. Disclosed heap content includes addresses suitable for defeating ASLR in further exploitation.

## 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. gdbserver has no authentication mechanism; exposure is limited only by network access to the gdbserver port.