Description
In the Linux kernel, the following vulnerability has been resolved:

net: dsa: mv88e6xxx: bound the policy rule dump by the caller's buffer size

mv88e6xxx_get_rxnfc() uses rxnfc->rule_cnt as the write index while
dumping the policy IDR, clobbering the input value before it has been
looked at. That input is the number of entries the caller had room for.
ETHTOOL_GRXCLSRLALL requires no CAP_NET_ADMIN and the ioctl sizes the
buffer from the rule_cnt userspace passes in, so once an admin has
installed policy rules any user can ask for fewer slots than there are
rules and run off the end of the allocation. A rule_cnt of 0 leaves the
buffer pointer NULL and the walk dereferences it.

Count into a local so the caller's limit survives the walk, and stop with
-EMSGSIZE once it is reached.
Published: 2026-09-25
Score: 7 High
EPSS: < 1% Very Low
KEV: No
Impact: Denial of Service via kernel crash
Action: Apply patch
AI Analysis

Impact

The mv88e6xxx driver in the Linux kernel incorrectly uses the caller‑supplied rule_cnt field as a write index before validating it. When an ETHTOOL_GRXCLSRLALL request specifies fewer slots than the number of policy rules installed, the driver writes past the end of the user buffer and can dereference a NULL pointer if rule_cnt is zero. This out‑of‑bounds write causes a memory corruption that results in a kernel crash and a denial of service.

Affected Systems

All Linux kernel installations that include the legacy mv88e6xxx driver are affected. Any distribution shipping a kernel that does not contain the patch is at risk, regardless of specific vendor or version details.

Risk and Exploitability

The ETHTOOL_GRXCLSRLALL ioctl that triggers the bug does not require CAP_NET_ADMIN, so any local user can exploit it without elevated privileges. The CVSS score of 7 indicates a medium severity. The EPSS score of < 1% shows a low probability of exploitation at this time, and the issue is not listed in the CISA KEV catalog. Consequently, the risk is primarily local denial of service rather than remote or privilege escalation.

Generated by OpenCVE AI on September 30, 2026 at 14:10 UTC.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Upgrade the kernel to a version that includes the mv88e6xxx driver patch from the Linux security team
  • If a kernel upgrade cannot be performed immediately, rebuild or replace the mv88e6xxx driver module to copy rule_cnt into a local variable before use and return –EMSGSIZE when the requested rule count exceeds the actual number
  • Configure SELinux, AppArmor, or device ACLs to restrict access to the ETHTOOL_GRXCLSRLALL ioctl for interfaces that use mv88e6xxx, allowing only privileged users to invoke it
  • Continuously monitor kernel logs (e.g., dmesg, /var/log/kern.log) for signs of segmentation faults or out‑of‑bounds writes and run periodic integrity checks to detect exploitation attempts

Generated by OpenCVE AI on September 30, 2026 at 14:10 UTC.

Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4817-1 linux-6.12 security update
Debian DLA Debian DLA DLA-4841-1 linux security update
Debian DSA Debian DSA DSA-6528-1 linux security update
Ubuntu USN Ubuntu USN USN-8961-1 Linux kernel vulnerabilities
History

Sat, 03 Oct 2026 11:15:00 +0000

Type Values Removed Values Added
References

Tue, 29 Sep 2026 13:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-787
References
Metrics threat_severity

None

 threat_severity

Moderate

Fri, 25 Sep 2026 22:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-120
CWE-129
CWE-20

Fri, 25 Sep 2026 15:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-120
CWE-129
CWE-20

Fri, 25 Sep 2026 15:00:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

Fri, 25 Sep 2026 10:30:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: net: dsa: mv88e6xxx: bound the policy rule dump by the caller's buffer size mv88e6xxx_get_rxnfc() uses rxnfc->rule_cnt as the write index while dumping the policy IDR, clobbering the input value before it has been looked at. That input is the number of entries the caller had room for. ETHTOOL_GRXCLSRLALL requires no CAP_NET_ADMIN and the ioctl sizes the buffer from the rule_cnt userspace passes in, so once an admin has installed policy rules any user can ask for fewer slots than there are rules and run off the end of the allocation. A rule_cnt of 0 leaves the buffer pointer NULL and the walk dereferences it. Count into a local so the caller's limit survives the walk, and stop with -EMSGSIZE once it is reached.
Title net: dsa: mv88e6xxx: bound the policy rule dump by the caller's buffer size
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-10-19T09:12:32.331Z

Reserved: 2026-09-25T10:19:56.070Z

Link: CVE-2026-98027

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-25T11:17:31.340

Modified: 2026-10-19T10:17:56.653

Link: CVE-2026-98027

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-09-25T00:00:00Z

Links: CVE-2026-98027 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-09-30T14:15:16Z

Weaknesses