HIGH CVSS 7.8
Published: 2026-06-25

CVE-2026-53265

linux linux_kernel Security Advisory (CVE-2026-53265)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-53265 impacting linux linux_kernel. Evaluated with CVSS Base Score of 7.8 (HIGH).

Original NVD Description

Source: NIST NVD
In the Linux kernel, the following vulnerability has been resolved: dm cache policy smq: check allocation under invalidate lock commit 2d1f7b65f5de ("dm cache policy smq: fix missing locks in invalidating cache blocks") added mq->lock around the destructive part of smq_invalidate_mapping(), but left the e->allocated check outside the critical section. That leaves a check-then-act race. Two concurrent invalidators can both observe e->allocated as true before either of them takes mq->lock. The first invalidator that acquires the lock removes the entry from the queues and hash table and then calls free_entry(), which clears e->allocated and puts the entry back on the free list. The second invalidator can then acquire mq->lock and continue with the stale result of the unlocked check. This can corrupt the SMQ queues or hash table by deleting an entry that is no longer on those structures. It can also hit the allocation check in free_entry() when the same entry is freed again. Move the allocation check under mq->lock so the predicate and the destructive operations are serialized by the same lock.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Local (AV:L)
Requires local system execution permissions
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
Low (PR:L)
Standard user access required
User Interaction
None (UI:N)
Zero human interaction required
Scope
Unchanged (S:U)
Confined to same security context
Confidentiality
High (C:H)
Total information disclosure
Integrity
High (I:H)
Total modification of target system
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product linux / linux_kernel
Affected Versions *
Weakness Enumeration NVD-CWE-noinfo

Security Research Arsenal: Nuclei Detection Template & PoC Exploit Probe

High-Intent Research Tool

Ready-to-use security scanner signatures, active verification probe skeletons, and remediation playbooks for CVE-2026-53265 impacting linux linux_kernel.

⚡ Nuclei Detection Template (YAML) cve-2026-53265.yaml
id: cve-2026-53265

info:
  name: linux linux_kernel - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: high
  description: |
    Automated signature & scanner for CVE-2026-53265 affecting linux linux_kernel.
    Evaluation: In the Linux kernel, the following vulnerability has been resolved:

dm cache policy smq: check allocation under invalidate lock

commit 2d1f7b65f5de ...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-53265
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 7.8
    cve-id: CVE-2026-53265
    cwe-id: NVD-CWE-noinfo
  tags: cve,cve-2026-53265,linux,linux_kernel,high

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "linux_kernel"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-53265.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-53265
# Target: linux linux_kernel | CVSS: 7.8 (HIGH)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-53265 (linux linux_kernel)...")
    headers = {
        "User-Agent": "CyberVault-Audit-Scanner/2.0",
        "Accept": "*/*"
    }
    try:
        r = requests.get(f"{target_url.rstrip('/')}/", headers=headers, timeout=8, verify=False)
        print(f"[+] Server Response: HTTP {r.status_code} | Server Banner: {r.headers.get('Server', 'Unknown')}")
        if r.status_code < 500:
            print(f"[!] Target reachable. Verify version against linux linux_kernel scope (*).")
        return True
    except Exception as e:
        print(f"[-] Connection Error: {e}")
        return False

if __name__ == '__main__':
    url = sys.argv[1] if len(sys.argv) > 1 else "http://localhost:8080"
    verify_vulnerability(url)
🛡️ Quick Patch & Remediation Script (Bash) patch_cve-2026-53265.sh
# Recommended Remediation & Patching Commands for CVE-2026-53265
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install linux_kernel 2>/dev/null || \
sudo dnf upgrade linux_kernel 2>/dev/null || \
sudo yum update linux_kernel

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i linux_kernel 2>/dev/null || rpm -qa | grep -i linux_kernel

# 3. Docker container & image vulnerability scan:
docker scan $(docker ps -q) 2>/dev/null || echo "Verify upstream base images in Dockerfile."

🛡️ Remediation & Security Action

  • Authoritative Guidance: Follow distribution-specific vendor security notices. Advisory status and package patches vary by distribution release.
  • Verification: Inspect installed binary packages and package manager versions for affected component releases.
  • Upstream Status: Upgrade to verified non-backdoored upstream versions or roll back to known-clean stable releases.
⚠️ Disclaimer: Follow vendor-specific advisories for your operating system. CyberVault does not fabricate unsupported remediation scripts.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-53265 in linux linux_kernel?

Review vendor-specific security notices and update linux linux_kernel packages to the latest patched release immediately. If immediate upgrading is restricted by change windows, isolate affected network ports and enforce least-privilege access boundaries.

Is there an active exploit or public PoC for CVE-2026-53265?

No weaponized public exploit has been confirmed in public threat streams yet. Continuous surveillance is active across GitHub and security feeds.

What is the CVSS 3.1 severity rating and impact for CVE-2026-53265?

CVE-2026-53265 is classified with a CVSS 3.1 Base Score of 7.8 (HIGH). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
7.8
HIGH SEVERITY
CVE ID CVE-2026-53265
Weakness NVD-CWE-noinfo
Vendor linux
Product linux_kernel
Published 2026-06-25
Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H