CVE-2025-38248VulnerabilityPublished 22 Apr 2026Updated 29 Oct 2026

Red Hat Security Advisory: kernel security update

Affects Linux kernelSource GCVE Database

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Mentioned vulnerabilities

Not known to be exploited.

Data as of 29 Oct 2026, 22:47 UTC

Severity

Medium

Rated by Threat Radar · No CVSS score from NVD or the CNA

EPSS: 0.2% chance of exploitation in 30 days – higher than 22% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation evidence

Disclosed: evidence found.
CVE published 22 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
Public exploit code: GitHub proofs of concept
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Red Hat Product Security Red Hat	Affected >=9.6 Red Hat Red Hat Enterprise Linux Red Hat Enterprise Linux AppStream E4S (v.9.2) Red Hat Enterprise Linux BaseOS E4S (v.9.2) s390x	Fixed in–

AI-suggested

For GKE users, upgrade Container-Optimized OS and Ubuntu node pools to the specified patch versions or later as listed in the advisory. Avoid using unconfined seccomp profiles or granting CAP_NET_ADMIN capability in Autopilot clusters to reduce exposure. For Red Hat Enterprise Linux 9.6 Extended Update Support, apply the kernel update provided in advisory RHSA-2026:5197 and reboot the system to activate the patch. For GKE on AWS, Azure, and VMware, monitor vendor advisories for forthcoming patch releases. No action is required for GDC bare metal software as it is not affected.

Description

The kernel packages contain the Linux kernel, the core of any Linux operating system. Security Fix(es): * kernel: Linux kernel:A use-after-free in bridge multicast in br_multicast_port_ctx_init (CVE-2025-38248) * kernel: Bluetooth: MGMT: Fix possible UAFs (CVE-2025-39981) * kernel: mlxsw: spectrum_mr: Fix use-after-free when updating multicast route stats (CVE-2025-68800) * kernel: Linux kernel: Denial of Service via unsafe requeue in rxrpc_recvmsg (CVE-2026-23066) * kernel: Linux kernel: Local denial of service and memory leak in DAMON sysfs via setup failure (CVE-2026-23144) * kernel: Linux kernel: Use-after-free in bonding module can cause system crash or arbitrary code execution (CVE-2026-23171) * kernel: macvlan: fix error recovery in macvlan_common_newlink() (CVE-2026-23209) * kernel: net/sched: cls_u32: use skb_header_pointer_careful() (CVE-2026-23204) * kernel: kernel: Privilege escalation or denial of service via use-after-free in nf_tables_addchain() (CVE-2026-23231) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Impact

Successful exploitation of CVE-2025-38248 can lead to privilege escalation on affected nodes, potentially allowing attackers to gain elevated privileges within the node's operating system. This impacts Container-Optimized OS and Ubuntu nodes in GKE Standard clusters and certain Autopilot cluster configurations. GKE Sandbox clusters and GDC bare metal software are not affected. Red Hat Enterprise Linux 9.6 Extended Update Support users are also impacted but have an available kernel update. No known exploits in the wild have been reported at this time.

Summary

CVE-2025-38248 is a use-after-free vulnerability in the Linux kernel's bridge multicast initialization function (br_multicast_port_ctx_init) that can lead to privilege escalation. This affects Container-Optimized OS and Ubuntu nodes running in Google Kubernetes Engine (GKE) Standard clusters, with potential impact on Autopilot clusters configured with unconfined seccomp or CAP_NET_ADMIN. GKE Sandbox clusters and GDC bare metal software are not affected. Red Hat Enterprise Linux 9.6 Extended Update Support kernel packages include fixes for this vulnerability. The Red Hat advisory (RHSA-2026:5197) also addresses a related use-after-free in macvlan (CVE-2026-23001). Patch versions for affected GKE node pools are provided, with instructions to upgrade to specific patch versions or later. For some GKE platforms (AWS, Azure, VMware), patch details are pending. The Red Hat update requires a reboot to take effect.

CWE-825Expired Pointer Dereference (opens in a new tab)
Base weakness
The product dereferences a pointer that contains a location for memory that was previously valid, but is no longer valid.
Architecture and Design
Choose a language that provides automatic memory management.
Implementation
When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-416Use After Free (opens in a new tab)
Variant weaknessLikelihood of exploit: HighCWE Top 25 (2025): #7
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
Architecture and Design · Language Selection
Choose a language that provides automatic memory management.
Implementation · Attack Surface Reduction
When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-772Missing Release of Resource after Effective Lifetime (opens in a new tab)
Base weaknessLikelihood of exploit: High
The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Implementation
It is good practice to be responsible for freeing all resources you allocate and to be consistent with how and where you free resources in a function. If you allocate resources that you intend to free upon completion of the function, you must be sure to free the resources at all exit points for that function including…
Operation · Architecture and Design · Resource Limitation
Use resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available.
Attack patterns
HTTP DoS (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-1285Improper Validation of Specified Index, Position, or Offset in Input (opens in a new tab)
Base weakness
The product receives input that is expected to specify an index, position, or offset into an indexable resource such as a buffer or file, but it does not validate or incorrectly validates that the specified index/position/offset has the required properties.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 4 Aug 2026, 13:07 UTC

Public exploits and detectionGitHub proofs of concept

WeaknessesCWE-825, CWE-416, CWE-772 +1

Technical details

References

Community reviews

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