CVE-2026-121996
Gdb: gdbserver: heap disclosure and wild pointer in gdb_parse_agent_expr via untrusted agent-expression length
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Gdb: gdbserver: heap disclosure and wild pointer in gdb_parse_agent_expr via untrusted agent-expression length
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.
- Record
CVE-2026-121996- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H - Weakness
- CWE-822
- Updated
- 2026-11-06
EUVDEUVD-2026-117573
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.
- Record
EUVD-2026-117573- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H - Updated
- 2026-11-06
GitHub AdvisoriesGHSA-px57-gjvm-vwfx
A length validation flaw in gdbserver's agent-expression parser allows an unauthenticated remote...
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.
- Record
GHSA-px57-gjvm-vwfx- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H - Weakness
- CWE-822
- Updated
- 2026-11-05
NVD
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.
- Record
CVE-2026-121996- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H - Weakness
- CWE-822
- Updated
- 2026-11-05
OSVDEBIAN-CVE-2026-121996
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.
- Record
DEBIAN-CVE-2026-121996- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H - Updated
- 2026-11-06
OSVUBUNTU-CVE-2026-121996
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.
- Record
UBUNTU-CVE-2026-121996- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H - Updated
- 2026-11-07
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
gdbDebian:12 |
All versions, plus listed versions 13.1-313.2-113.2-1+hurd.315.1-115.2-1 Show 36 moreShow less15.2-2~exp116.0.90.20250111-1~exp116.0.90.20250111-1~exp216.1-116.1-216.1-2+hurd.116.2-116.2-216.2-316.2-416.2-516.2-616.2-716.2-816.3-116.3-216.3-316.3-416.3-4~bpo13+116.3-4~bpo13+216.3-516.3-5~bpo13+117.0.50.20250905-1~exp117.0.90-1~exp117.0.90-1~exp217.1-117.1-1~bpo13+117.1-217.1-317.1-417.2-117.2-1~bpo13+118.1-118.1-218.1-318.1-3~bpo13+1 |
None known |
gdbDebian:13 |
All versions, plus listed versions 16.3-116.3-216.3-316.3-416.3-4~bpo13+1 Show 17 moreShow less16.3-4~bpo13+216.3-516.3-5~bpo13+117.0.50.20250905-1~exp117.0.90-1~exp117.0.90-1~exp217.1-117.1-1~bpo13+117.1-217.1-317.1-417.2-117.2-1~bpo13+118.1-118.1-218.1-318.1-3~bpo13+1 |
None known |
gdbDebian:14 |
All versions, plus listed versions 16.3-116.3-216.3-316.3-416.3-4~bpo13+1 Show 17 moreShow less16.3-4~bpo13+216.3-516.3-5~bpo13+117.0.50.20250905-1~exp117.0.90-1~exp117.0.90-1~exp217.1-117.1-1~bpo13+117.1-217.1-317.1-417.2-117.2-1~bpo13+118.1-118.1-218.1-318.1-3~bpo13+1 |
None known |
gdbUbuntu:Pro:16.04:LTS |
All versions, plus listed versions 7.10-1ubuntu27.10-1ubuntu37.10.1-0ubuntu17.10.90.20160215-0ubuntu27.10.90.20160220-0ubuntu1 Show 4 moreShow less7.11-0ubuntu17.11.1-0ubuntu1~16.047.11.1-0ubuntu1~16.57.11.1-0ubuntu1~16.5+esm1 |
None known |
gdbUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 8.0.1-0ubuntu18.0.1-0ubuntu28.0.1-0ubuntu38.1-0ubuntu18.1-0ubuntu2 Show 5 moreShow less8.1-0ubuntu38.1-0ubuntu3.18.1-0ubuntu3.28.1.1-0ubuntu18.1.1-0ubuntu1+esm1 |
None known |
gdbUbuntu:20.04:LTS |
All versions, plus listed versions 8.3-0ubuntu19.0.50.20191019-0ubuntu19.0.50.20191119-0ubuntu19.0.90.20191216-0ubuntu19.0.90.20200105-0ubuntu1 Show 5 moreShow less9.0.90.20200117-0ubuntu19.1-0ubuntu19.2-0ubuntu1~20.049.2-0ubuntu1~20.04.19.2-0ubuntu1~20.04.2 |
None known |
gdbUbuntu:22.04:LTS |
All versions, plus listed versions 11.1-0ubuntu211.1-0ubuntu311.2-0ubuntu112.0.50.20220217-0ubuntu112.0.90-0ubuntu112.1-0ubuntu1~22.0412.1-0ubuntu1~22.04.2 |
None known |
gdbUbuntu:24.04:LTS |
All versions, plus listed versions 14.0.50.20230907-0ubuntu114.1-0ubuntu114.1-0ubuntu215.0.50.20240219-0ubuntu115.0.50.20240320-0ubuntu115.0.50.20240403-0ubuntu115.1-1ubuntu1~24.04.1 |
None known |
gdbUbuntu:26.10 |
All versions, plus listed versions 17.1-2ubuntu117.2-1ubuntu1 |
None known |
gdbUbuntu:26.04:LTS |
All versions, plus listed versions 16.3-1ubuntu216.3-5ubuntu117.1-1ubuntu117.1-1ubuntu217.1-2ubuntu1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, aliases, references | CVE List, EUVD, OSV | |
| affected, aliases, references | CVE List, EUVD, NVD, OSV | |
| aliases, references | GitHub Advisories | |
| aliases, published | EUVD | |
| first indexed | CVE List |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-121996 is a high vulnerability (CVSS 8.2) in Red Hat Enterprise Linux 10, published November 5, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.47%, the 40th percentile. No source names a fixed version.