Cyber Resilience

CVE-2023-5633

Memory Safety in Linux Kernel 6.1.13 – 6.1.75

Published
23 October 2023
Modified
25 February 2026
Patch / 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 21th percentile
Risk Priority 56 floored blend · peak EPSS

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 Exploitation for Client Execution (T1203); ranked at the 21th 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)

Related Threats

MITRE ATT&CK Enterprise Techniques

T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
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-2023-2513Same product: Linux Linux Kernel
CVE-2023-4387Same product: Linux Linux Kernel
CVE-2023-1192Same product: Linux Linux Kernel
CVE-2024-0562Same product: Linux Linux Kernel
CVE-2024-0775Same product: Linux Linux Kernel
CVE-2023-1652Same product: Linux Linux Kernel
CVE-2026-53006Same product: Linux Linux Kernel
CVE-2023-4806Same product: Redhat Codeready Linux Builder Eus

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.

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.

PR.PS-06 mostly match
prevents

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

ID.RA-01 partial match
prevents

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

PR.PS-02 partial match
prevents

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

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.

finds

Security testing in development can detect reference-count defects before release, providing partial mitigation.

prevents

Secure development lifecycle practices can include reference-counting rules and automated checks that reduce the likelihood of improper updates.

prevents

Application security requirements can mandate correct resource-lifetime management, indirectly addressing reference-count errors.

prevents

Secure system architecture principles encourage explicit resource-ownership models that mitigate reference-count misuse.

prevents

Secure coding standards directly prescribe correct increment/decrement patterns, covering most instances of this weakness.

prevents

Change-management processes may catch reference-count issues introduced by modifications, but do not address the root coding flaw.

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` (authoritative 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. prevents CWE-416
RHEL 8 (1 rule)
  • V-230279 RHEL 8 must clear memory when it is freed to prevent use-after-free attacks. prevents CWE-416
RHEL 9 (1 rule)
  • V-257794 RHEL 9 must clear memory when it is freed to prevent use-after-free attacks. prevents CWE-416

References