CVSS 3.1
8.2 highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:HCVE-2026-121996
High (8.2). EPSS 0.5% estimated probability of exploitation activity in the next 30 days.
On this page
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.
Severity
- EPSS
- 0.5% estimated probability of exploitation activity in the next 30 days; 41st percentile. Scored 2026-11-10. A forecast for this CVE across the internet, not for your own systems.
- CISA's assessment (SSVC)
- Exploitation: none · Automatable: yes · Technical impact: partial, assessed 2026-11-05. From CISA's Vulnrichment in the CVE List: whether it is exploited, whether exploiting it can be automated, and how much control it gives.
- CWE
- CWE-822 Untrusted Pointer Dereference
- Published
- Modified
- NVD analysis
- Awaiting analysis
- Record from
- the NVD, synced
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Explain CVE-2026-121996 for an engineer deciding whether to act. Use https://cve.bz/api/public/cves/CVE-2026-121996?via=ask-ai-copy and https://cve.bz/cve/CVE-2026-121996?via=ask-ai-copy as the source of truth: what is affected and which versions fix it, whether it is in CISA KEV, public exploits, and its EPSS (an internet-wide 30-day estimate of exploitation activity, not a forecast for my systems). If they give no fixed versions, use the CVE record https://cveawg.mitre.org/api/cve/CVE-2026-121996 or the vendor advisory, not third-party mirrors. Tell me how to check whether I am affected and how to verify a fix. Cite the sources and say where they are uncertain.Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this CVE's id and public links.
Linux distributions
| Distribution | Release | Package | Fixed in | Advisory |
|---|---|---|---|---|
| Debian | 12, 13, 14 | gdb | no fix listed | DEBIAN-CVE-2026-121996 |
| Ubuntu | 20.04:LTS, 22.04:LTS, 24.04:LTS and 4 more | gdb | no fix listed | UBUNTU-CVE-2026-121996 |
From the distributions' data via OSV.dev: the Debian Security Tracker; Ubuntu Security Notices © Canonical Ltd., CC BY-SA 4.0. Modified: reformatted and linked to CVE records. Credits. On the distributions' own pages: Debian · Ubuntu.
Red Hat
Red Hat rates this Important.
This flaw is present in gdbserver as shipped with Red Hat Enterprise Linux. An attacker with network access to an exposed gdbserver port can exploit this without authentication or user interaction to disclose heap memory contents or crash gdbserver.
There is no mitigation for this vulnerability. gdbserver has no authentication mechanism; exposure is limited only by network access to the gdbserver port.
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 10 | crash | Not affected | |
| Red Hat Enterprise Linux 10 | gdb | Affected | |
| Red Hat Enterprise Linux 6 | gdb | Affected | |
| Red Hat Enterprise Linux 7 | gdb | Affected | |
| Red Hat Enterprise Linux 8 | crash | Not affected | |
| Red Hat Enterprise Linux 8 | gcc-toolset-14-gdb | Affected | |
| Red Hat Enterprise Linux 8 | gcc-toolset-15-gdb | Affected | |
| Red Hat Enterprise Linux 8 | gdb | Affected | |
| Red Hat Enterprise Linux 9 | crash | Not affected | |
| Red Hat Enterprise Linux 9 | gdb | Affected | |
| Red Hat Hardened Images | gdb | Affected |
Contains Red Hat Security Data © Red Hat, Inc., licensed under CC BY 4.0. Source: https://access.redhat.com/security/data. Modified: reformatted. Red Hat's page for CVE-2026-121996.
Attack patterns (CAPEC)
- CAPEC-129 Pointer Manipulation Severity: Medium
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.