What is the CVSS score of CVE-2026-23245?

CVE-2026-23245 has a CVSS 3.1 base score of 7.8 (High). CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

How to fix or mitigate CVE-2026-23245?

Within 24 hours: Inventory all systems running Linux kernel 5.8 through 7.0-rc3, prioritizing production and security-critical infrastructure. Within 7 days: Apply vendor patches-upgrade to kernel 6.18.18, 6.19.8, or 7.0-rc3 or later on all affected systems. Within 30 days: Complete patching across entire infrastructure and verify no systems remain on vulnerable kernel versions through automated compliance scanning.

Linux CVE-2026-23245

Q: Which versions of Linux are affected by CVE-2026-23245?

CVE-2026-23245 is a high-severity race condition in the Linux kernel's Traffic Control scheduler that allows authenticated local users to corrupt memory and potentially execute arbitrary code or…. A patch is available.

EUVD-2026-12808 HIGH

2026-03-18 Linux

Information Disclosure Linux

7.8

CVSS 3.1 · Vendor: Linux

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Recon

Obtain local shell with CAP_NET_ADMIN
Delivery

Create act_gate TC rule on interface
Exploit

Trigger concurrent packet processing
Install

Issue rapid TC_ACT_REPLACE commands
C2

Win race condition triggering use-after-free
Execute

Corrupt kernel memory with controlled data
Impact

Execute arbitrary code in kernel context
Step 8

Escalate to root privileges

Vulnerability Assessment

Exploitation Conditions	Requires local authenticated access with CAP_NET_ADMIN capability or equivalent permissions to configure Traffic Control rules (typically root or users in specific privileged groups). Exploitation requires the act_gate kernel module to be loaded and the attacker must be able to create and replace gate actions on network interfaces. This is NOT exploitable in default kernel configurations where unprivileged users cannot modify Traffic Control settings. The race condition has low attack complexity (AC:L) but requires precise timing to win the race between replacement and callback/dump operations, suggesting exploitation may require multiple attempts. Systems that do not use act_gate for time-aware scheduling or that restrict TC configuration to trusted administrators are not at practical risk.
Impact	Real-world risk is moderate-to-low despite the CVSS 7.8 HIGH rating. The vulnerability requires local authenticated access (PR:L) and specific networking configuration using Traffic Control with act_gate actions, which is not a default kernel feature. EPSS score of 0.02% (4th percentile) indicates extremely low predicted exploitation probability in the wild, consistent with the specialized nature of the affected subsystem. No entries in CISA KEV and no public exploit code identified, suggesting this has not been weaponized. However, the technical impact is severe (C:H/I:H/A:H) - successful exploitation could allow a low-privileged local user to escalate privileges to kernel level through memory corruption. Primary risk is in multi-tenant environments (containers, cloud instances) where untrusted local users have CAP_NET_ADMIN or equivalent permissions to configure Traffic Control rules. Organizations not using act_gate scheduling or restricting TC configuration to root can deprioritize this below remotely exploitable vulnerabilities.
Exploit ScenarioDerived	A malicious local user with CAP_NET_ADMIN capability on a multi-tenant system creates a Traffic Control gate action on a network interface, then rapidly issues TC_ACT_REPLACE commands to swap gate parameters while simultaneously triggering packet processing that invokes the hrtimer callback. By winning the race condition, the attacker causes the kernel to dereference freed memory from the old schedule list, leading to memory corruption. The attacker leverages heap spraying techniques to control the contents of the freed region, achieving arbitrary kernel code execution and escalating to root privileges.

Act Now Prioritize within 24-48h. Why: Active threat signals + CRITICAL/HIGH severity.

Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv3 – Apr 18, 2026

Race condition in Linux kernel's Traffic Control act_gate scheduler allows local authenticated users to trigger memory corruption and potentially execute arbitrary code or cause denial of service. Affects Linux kernel 5.8+ through 6.19.x and 7.0-rc3. Vulnerability arises when concurrent gate action replacement occurs during hrtimer callback or dump operations, creating a use-after-free scenario. No active exploitation confirmed (EPSS 0.02%, not in CISA KEV). Vendor patches available across multiple stable branches including 6.18.18, 6.19.8, and 7.0-rc3.

Earlier versions of this analysis (2)

v2 Apr 18, 2026 - 09:44 cvss changed CVSS 7.8

Race condition in Linux kernel act_gate traffic control action (5.8+) allows local authenticated attackers to trigger use-after-free via concurrent parameter replacement during hrtimer callback or schedule list traversal, potentially achieving privilege escalation to kernel context. Affects widely deployed kernel versions with tc-gate QoS feature enabled. Vendor patches available across stable branches (6.18.18, 6.19.8, 7.0-rc3). EPSS 0.02% suggests low observed exploitation; no KEV listing or public POC identified at time of analysis.

v1 Mar 18, 2026 - 10:30 CVSS 7.8

A race condition vulnerability exists in the Linux kernel's net/sched act_gate module where the hrtimer callback or dump path can access schedule list parameters while they are being replaced, leading to potential use-after-free or memory corruption. The vulnerability affects Linux kernel versions across multiple release branches including 5.8 and later stable releases up to 6.19.8, with the fix implemented through RCU-protected parameter snapshots. This is a kernel-level race condition that could allow local attackers with network scheduler configuration privileges to cause denial of service or potentially achieve code execution through memory corruption.

RemediationAI

Upgrade to patched Linux kernel versions: 6.18.18 or later in the 6.18.x series, 6.19.8 or later in the 6.19.x series, or 7.0-rc3 or later in the development branch. Patch commits available at https://git.kernel.org/stable/c/04d75529dc0f9be78786162ebab7424af4644df2 (6.19.8), https://git.kernel.org/stable/c/58b162e318d0243ad2d7d92456c0873f2494c351 (7.0-rc3), and https://git.kernel.org/stable/c/62413a9c3cb183afb9bb6e94dd68caf4e4145f4c (mainline). If immediate patching is not feasible, disable the act_gate Traffic Control action by blacklisting the act_gate kernel module or restricting CAP_NET_ADMIN capability in containerized environments to prevent untrusted users from configuring TC rules. Note that disabling act_gate will break time-aware traffic scheduling for TSN (Time-Sensitive Networking) or 802.1Qbv implementations. For production systems requiring act_gate functionality, prioritize kernel updates and audit which users/containers have CAP_NET_ADMIN permissions.

Affected VersionsENISA

Linux a51c328df3106663879645680609eb49b3ff6444 <58b162e318d0243ad2d7d92456c0873f2494c351

Linux patch: 7.0-rc3

Linux 5.8

Linux a51c328df3106663879645680609eb49b3ff6444 <04d75529dc0f9be78786162ebab7424af4644df2

Linux patch: 6.19.8

Linux patch: 0

Linux patch: 6.18.18

Linux a51c328df3106663879645680609eb49b3ff6444 <62413a9c3cb183afb9bb6e94dd68caf4e4145f4c

Affected Packages

euvd linux no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The act_gate Traffic Control action in Linux implements time-aware scheduling for network packets, using high-resolution timers (hrtimer) to manage gate schedules. The vulnerability stems from insufficient synchronization when replacing gate action parameters. When an existing gate action is replaced via the TC_ACT_REPLACE operation, the new parameters can be swapped in while concurrent code paths (hrtimer callback processing packets, or netlink dump operations enumerating the schedule list) are still walking the schedule data structures. Without proper RCU (Read-Copy-Update) protection, this creates a classic time-of-check-time-of-use race condition where freed memory can be accessed. The fix implements RCU snapshots of parameters, atomic pointer swapping under tcf_lock, and deferred reclamation via call_rcu(). This is a use-after-free vulnerability class, though no CWE was formally assigned by NVD.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (Linux) PRIMARY 7.8 HIGH

AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

SUSE HIGH

Primary rating from Vendor (Linux).

CVSS VectorVendor: Linux

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Updated

Apr 18, 2026 - 09:44 vuln.today

v3 - CVSS changed

Analysis Updated

Apr 18, 2026 - 09:44 vuln.today

v2 - CVSS changed

Patch released

Mar 31, 2026 - 21:13 nvd

Patch available

CVE Published

Mar 18, 2026 - 10:05 nvd

HIGH 7.8

DescriptionCVE.org

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

net/sched: act_gate: snapshot parameters with RCU on replace

The gate action can be replaced while the hrtimer callback or dump path is walking the schedule list.

Convert the parameters to an RCU-protected snapshot and swap updates under tcf_lock, freeing the previous snapshot via call_rcu(). When REPLACE omits the entry list, preserve the existing schedule so the effective state is unchanged.

Executive ViewAI

Why It Matters

CVE-2026-23245 is a high-severity race condition in the Linux kernel's Traffic Control scheduler that allows authenticated local users to corrupt memory and potentially execute arbitrary code or crash systems. Organizations running Linux kernel versions 5.8 through 7.0-rc3 face elevated risk of lateral movement and service disruption if an attacker gains local access. Patching is critical for systems where local user access cannot be strictly controlled.

Business Impact: High

Compensating Controls

Apply vendor patch. If immediate patching is not feasible, restrict local user access through strict account provisioning policies and disable unprivileged user namespaces via sysctl (user.max_user_namespaces=0) to reduce local attack surface until patches are deployed.

Threat Intelligence Overview

EPSS Score

0.0%

Top 96% exploitable

Threat Intel

1 source

Data Quality

7 sources

Confidence: High

EUVD

NVD

CVE.org

EPSS CISA Vendor

VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC No

EPSS 0.0%

Patch available Yes

Active threat Yes

Deciding rule

Active threat signals + CRITICAL/HIGH severity

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Small

Automatable· derived

Human Impact

High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +39

PoC: 0

Weaponized: 0

Threat intel: +10

Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Related Vulnerabilities in Linux Kernel Memory and Bounds Check Flaws

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CVE-2026-23247 MEDIUM

Same technique Information Disclosure

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CVE-2019-2725 CRITICAL POC

9.8

CVE-2021-34523 CRITICAL POC

9.0

CVE-2013-2251 CRITICAL POC

9.8

CVE-2017-5638 CRITICAL POC

9.8

CVE-2025-24813 CRITICAL POC

9.8

CVE-2025-68613 HIGH POC

8.8

CVE-2015-1701 HIGH POC

7.8

CVE-2017-0147 HIGH POC

7.5

Vendor StatusVendor

Debian

linux

Release	Status	Fixed Version	Urgency
bullseye	vulnerable	5.10.223-1	-
bullseye (security)	vulnerable	5.10.251-1	-
bookworm	vulnerable	6.1.159-1	-
bookworm (security)	vulnerable	6.1.164-1	-
trixie	vulnerable	6.12.73-1	-
trixie (security)	vulnerable	6.12.74-2	-
forky	vulnerable	6.19.6-2	-
sid	fixed	6.19.8-1	-
(unstable)	fixed	6.19.8-1	-

SUSE

Severity: High

Product	Status
SUSE Linux Enterprise Desktop 15 SP7	Fixed
SUSE Linux Enterprise Desktop 15 SP7	Fixed
SUSE Linux Enterprise High Availability Extension 15 SP7	Fixed
SUSE Linux Enterprise High Availability Extension 15 SP7	Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7	Fixed

Threat IntelligenceMISP

CISA Advisories

ICSA-26-209-04 ICSA-26-295-11 ICSA-26-295-16

Sources: CISA (public domain)

References

Advisories & patches

ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-23245 ADVISORY https://ubuntu.com/security/notices/USN-8567-1 ADVISORY https://vuldb.com/?id.351521 REF https://cert-portal.siemens.com/productcert/html/ssa-019113.html REF https://cert-portal.siemens.com/productcert/html/ssa-082556.html REF https://cert-portal.siemens.com/productcert/html/ssa-457936.html REF https://cert-portal.siemens.com/productcert/html/ssa-784472.html REF https://git.kernel.org/stable/c/035d0d09d5ab3ed3e93d18cde2b562a6719eea23 REF https://git.kernel.org/stable/c/04d75529dc0f9be78786162ebab7424af4644df2 REF https://git.kernel.org/stable/c/58b162e318d0243ad2d7d92456c0873f2494c351 REF https://git.kernel.org/stable/c/62413a9c3cb183afb9bb6e94dd68caf4e4145f4c REF https://git.kernel.org/stable/c/8b1251bbf0f10ac745ed74bad4d3b433caa1eeae REF https://git.kernel.org/stable/c/dfc314d7c767e350f78a46a8f8b134f80e8ad432 REF https://git.kernel.org/stable/c/fc98fd8d214693be91253d9a88cdf8e5e143d124

Search Externally

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