CVE-2025-38248Public exploit

Local privilege escalation via stale router-port entries

Published Jul 9, 2025 · Updated Aug 5, 2026

Use-after-free in the Linux bridge multicast code allows local users to escalate privileges through router-port configuration. During port or VLAN deletion, br_multicast_port_ctx_deinit() fails to remove a permanent router-port entry from the relevant list, so later traversal reads and writes freed slab memory. An unprivileged local user can obtain CAP_NET_ADMIN in a user and network namespace and trigger the deterministic sequence, enabling kernel-memory disclosure, controlled writes, a crash, or privilege escalation.

CVSS severity7.8
High
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Linux bridge multicast code allows local users to escalate privileges through router-port configuration. During port or VLAN deletion, br_multicast_port_ctx_deinit() fails to remove a permanent router-port entry from the relevant list, so later traversal reads and writes freed slab memory. An unprivileged local user can obtain CAP_NET_ADMIN in a user and network namespace and trigger the deterministic sequence, enabling kernel-memory disclosure, controlled writes, a crash, or privilege escalation.

The record

CVE
CVE-2025-38248
Published
Jul 9, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 9, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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  1. Affected versionversion=2796d846d74a18cc6563e96eff8bf28c5e06f912 <4d3c2a1d4c7c33103f1ddfdbc5cfe1ea4f6d0dcd
  2. Affected versionversion=2796d846d74a18cc6563e96eff8bf28c5e06f912 <7544f3f5b0b58c396f374d060898b5939da31709
  3. Affected versionversion=2796d846d74a18cc6563e96eff8bf28c5e06f912 <bdced577da71b118b6ed4242ebd47f81bf54d406
  4. Affected versionversion=2796d846d74a18cc6563e96eff8bf28c5e06f912 <f05a4f9e959e0fc098046044c650acf897ea52d2
  5. Affected versionversion=5.15

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2796d846d74a18cc6563e96eff8bf28c5e06f912 <4d3c2a1d4c7c33103f1ddfdbc5cfe1ea4f6d0dcd; version=2796d846d74a18cc6563e96eff8bf28c5e06f912 <7544f3f5b0b58c396f374d060898b5939da31709; version=2796d846d74a18cc6563e96eff8bf28c5e06f912 <bdced577da71b118b6ed4242ebd47f81bf54d406; version=2796d846d74a18cc6563e96eff8bf28c5e06f912 <f05a4f9e959e0fc098046044c650acf897ea52d2; version=5.15

Published CVSS scores

7.8Linux Kernel CVE TeamCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-416Use After Free
T1068Exploitation for Privilege Escalation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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