Vulnerability · Published Nov 5, 2026 · Assigned by redhat
CVE-2026-121996Gdb: gdbserver: heap disclosure and wild pointer in gdb_parse_agent_expr via untrusted agent-expression length
High 8.2
In plain English
A high-severity security flaw in Red Hat Enterprise Linux 10 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities).
Severity (CVSS 3.1)8.2High
Exploit odds (30 days)0.5%top 59.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | gdb | no fix listed | DEBIAN-CVE-2026-121996 |
| Debian:13 | gdb | no fix listed | DEBIAN-CVE-2026-121996 |
| Debian:14 | gdb | no fix listed | DEBIAN-CVE-2026-121996 |
| Ubuntu:22.04:LTS | gdb | no fix listed | UBUNTU-CVE-2026-121996 |
| Ubuntu:24.04:LTS | gdb | no fix listed | UBUNTU-CVE-2026-121996 |
| Ubuntu:26.04:LTS | gdb | no fix listed | UBUNTU-CVE-2026-121996 |
| Ubuntu:26.10 | gdb | no fix listed | UBUNTU-CVE-2026-121996 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 | see references |
| Red Hat | Red Hat Enterprise Linux 10 | see references |
| Red Hat | Red Hat Enterprise Linux 6 | see references |
| Red Hat | Red Hat Enterprise Linux 7 | see references |
| Red Hat | Red Hat Enterprise Linux 8 | see references |
| Red Hat | Red Hat Enterprise Linux 8 | see references |
| Red Hat | Red Hat Enterprise Linux 8 | see references |
| Red Hat | Red Hat Enterprise Linux 8 | see references |
| Red Hat | Red Hat Enterprise Linux 9 | see references |
| Red Hat | Red Hat Enterprise Linux 9 | see references |
| Red Hat | Red Hat Hardened Images | see references |
Weakness: CWE-822 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
References
- https://access.redhat.com/security/cve/CVE-2026-121996 vdb-entry, x_refsource_REDHAT
- RHBZ#2565678 issue-tracking, x_refsource_REDHAT