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Fencer Vulns
high 8.2

CVE-2026-121996 json

Gdb: gdbserver: heap disclosure and wild pointer in gdb_parse_agent_expr via untrusted agent-expression length

published 2026-11-05 4 d ago modified 2026-11-06 2 d ago also EUVD-2026-117573

cvss
8.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 40%
public exploits
0
none known

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 addresses suitable for defeating ASLR in further exploitation.

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-121996 updated cvss 8.2

gdb: gdbserver: heap disclosure and wild pointer in gdb_parse_agent_expr via untrusted agent-expression length

  • Red Hat Enterprise Linux 6 gdb, gdb-gdbserver, gdb 17.2-4.el10_3 Red Hat Enterprise Linux 7 gdb-gdbserver, gdb 17.2-4.el10_3 Red Hat Enterprise Linux 8 gdb, gdb-headless, gdb-gdbserver, gdb 17.2-4.el10_3, gcc-toolset-14-gdb 14.2-3.el8_10, gcc-toolset-15-gdb 16.3-1.el8_10 Red Hat Enterprise Linux 9 gdb, gdb-minimal, gdb-headless, gdb-gdbserver, gdb 17.2-4.el10_3 Red Hat Enterprise Linux 10 gdb 17.2-4.el10_3 Red Hat Hardened Images gdb 17.2-4.el10_3
    affected: workaround, no fix available
  • Red Hat Enterprise Linux 8 crash 8.0.6-1.el10 Red Hat Enterprise Linux 9 crash 8.0.6-1.el10 Red Hat Enterprise Linux 10 crash 8.0.6-1.el10
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
3 d ago

Exploit prediction

0.47% chance of exploitation in the next 30 days, higher than 40% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

Affected products

  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Hardened Images

Classification

Weakness
  • CWE-822 Untrusted Pointer Dereference

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.