Security Resilience

CVE-2023-5633

Memory Safety in Linux Kernel 6.1.13 – 6.1.75

Memory Safety
Published
23 October 2023
Modified
25 February 2026
Patch / advisory
View advisory
CVSS Score v3.1 7.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0028 19th percentile
Risk Priority 56 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-5633 is a high-severity Improper Update of Reference Count (CWE-911) vulnerability in Linux Linux Kernel. Its CVSS base score is 7.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Data Obfuscation (T1001); ranked at the 19th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability Data

The reference count changes made as part of the CVE-2023-33951 and CVE-2023-33952 fixes exposed a use-after-free flaw in the way memory objects were handled when they were being used to store a surface. When running inside a VMware guest with…

more

3D acceleration enabled, a local, unprivileged user could potentially use this flaw to escalate their privileges.

CWE(s)
CWE-911CWE-416

Related Threats

MITRE ATT&CK Enterprise Techniques

T1001 Data Obfuscation Command And Control
Adversaries may obfuscate command and control traffic to make it more difficult to detect.
attack.mitre.org →
T1003 OS Credential Dumping Credential Access
Adversaries may attempt to dump credentials to obtain account login and credential material, normally in the form of a hash or a clear text password.
attack.mitre.org →
T1003.001 LSASS Memory Credential Access
Adversaries may attempt to access credential material stored in the process memory of the Local Security Authority Subsystem Service (LSASS).
attack.mitre.org →
T1003.004 LSA Secrets Credential Access
Adversaries with SYSTEM access to a host may attempt to access Local Security Authority (LSA) secrets, which can contain a variety of different credential materials, such as credentials for service accounts.
attack.mitre.org →
T1003.005 Cached Domain Credentials Credential Access
Adversaries may attempt to access cached domain credentials used to allow authentication to occur in the event a domain controller is unavailable.
attack.mitre.org →
T1005 Data from Local System Collection
Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-0193Same product: Linux Linux Kernel
CVE-2023-1476Same product: Linux Linux Kernel
CVE-2026-52943Same product: Linux Linux Kernel
CVE-2023-4387Same product: Linux Linux Kernel
CVE-2024-0562Same product: Linux Linux Kernel
CVE-2023-2513Same product: Linux Linux Kernel
CVE-2024-0775Same product: Linux Linux Kernel
CVE-2023-1192Same product: Linux Linux Kernel
CVE-2023-1652Same product: Linux Linux Kernel
CVE-2023-2019Same product: Linux Linux Kernel

Affected Assets

linux
linux kernel
6.6 · 6.1.13 — 6.1.75 · 6.2 — 6.5.8
redhat
codeready linux builder
8.0, 9.0
redhat
codeready linux builder eus
8.8, 9.2, 9.4
redhat
codeready linux builder for arm64
8.0_aarch64, 9.0_aarch64
redhat
codeready linux builder for arm64 eus
8.8_aarch64, 9.2_aarch64, 9.4_aarch64
redhat
codeready linux builder for ibm z systems
9.0_s390x
redhat
codeready linux builder for ibm z systems eus
9.2_s390x, 9.4_s390x
redhat
codeready linux builder for power little endian
8.0_ppc64le, 9.0_ppc64le
redhat
codeready linux builder for power little endian eus
8.8_ppc64le, 9.2_ppc64le, 9.4_ppc64le
redhat
enterprise linux
8.0, 9.0
+12 more product configuration(s) — see NVD for full list

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 3 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V1.4.3

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SI-16 Memory Protection
addresses: CWE-416

Use-after-free exploits that achieve arbitrary code execution are blocked or significantly hardened by non-executable pages and ASLR.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

ID.RA-01 partial match
blocks

Vulnerability identification processes can discover use-after-free issues via scanning or analysis but do not prevent their introduction.

PR.PS-02 partial match
blocks

Routine patching removes known use-after-free instances after they have been introduced in released software.

PR.PS-06 partial match
blocks

Secure SDLC practices directly prevent reference-count coding errors via reviews, static analysis, and testing.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.14 Information transfer partial match
removes
A.5.15 Access control partial match
removes
A.5.16 Identity management partial match
removes
A.5.17 Authentication information partial match
removes
A.5.18 Access rights partial match
removes
A.5.30 ICT readiness for business continuity partial match
removes

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (higher-evidence rows only; rows rated `none` are excluded).

Oracle Linux 8 (1 rule)
  • V-248592 OL 8 must clear memory when it is freed to prevent use-after-free attacks. blocks CWE-416
RHEL 8 (1 rule)
  • V-230279 RHEL 8 must clear memory when it is freed to prevent use-after-free attacks. blocks CWE-416
RHEL 9 (1 rule)
  • V-257794 RHEL 9 must clear memory when it is freed to prevent use-after-free attacks. blocks CWE-416

References