MEDIUM CVSS 4.2
Published: 2026-06-05

CVE-2026-48104

7-zip 7-zip Security Advisory (CVE-2026-48104)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-48104 impacting 7-zip 7-zip. Evaluated with CVSS Base Score of 4.2 (MEDIUM).

Original NVD Description

Source: NIST NVD
7-Zip is a file archiver with a high compression ratio. Versions 9.18 through 26.00 contain an uninitialized heap read in the SquashFS archive handler caused by a sparsely populated index array. In the SquashFS handler, _blockToNode is allocated with capacity for every metadata block but populated only when an inode crosses a block boundary, so a crafted image with few inodes spanning many blocks leaves most slots holding raw heap contents (the underlying allocator does not zero-initialize POD storage). When OpenDir looks up an attacker-influenced blockIndex (derived from the RootInode superblock field), it reads two of these uninitialized slots and passes them as the left/right bounds of a binary search over _nodesPos, which dereferences the midpoint without bounds checking; if the resulting value happens to match the search key, the returned index is used to read a full node struct from _nodes whose fields feed further directory parsing, forming a chained OOB read primitive that is heap-layout-dependent and not reliably triggerable. The SquashFS handler is enabled by default in stock 7z.dll and the issue triggers during Open() with no interaction beyond opening the file; impact is denial of service from wild-pointer dereference and potential heap information disclosure, with no write primitive. Version 26.01 fixes the issue.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
High (AC:H)
Depends on race conditions or environment
Privileges Required
None (PR:N)
Unauthenticated execution
User Interaction
Required (UI:R)
User must click or open resource
Scope
Unchanged (S:U)
Confined to same security context
Confidentiality
Low (C:L)
Partial information leakage
Integrity
None (I:N)
No system modification impact
Availability
Low (A:L)
Partial service performance degradation

🎯 Affected Versions Matrix

Affected Product 7-zip / 7-zip
Affected Versions *
Weakness Enumeration CWE-125

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-2026-48104 impacting 7-zip 7-zip.

⚡ Nuclei Detection Template (YAML) cve-2026-48104.yaml
id: cve-2026-48104

info:
  name: 7-zip 7-zip - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-48104 affecting 7-zip 7-zip.
    Evaluation: 7-Zip is a file archiver with a high compression ratio. Versions 9.18 through 26.00 contain an uninitialized heap read in the SquashFS archive handler...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-48104
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:L
    cvss-score: 4.2
    cve-id: CVE-2026-48104
    cwe-id: CWE-125
  tags: cve,cve-2026-48104,7-zip,7-zip,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "7-zip"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-48104.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-48104
# Target: 7-zip 7-zip | CVSS: 4.2 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-48104 (7-zip 7-zip)...")
    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 7-zip 7-zip 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-2026-48104.sh
# Recommended Remediation & Patching Commands for CVE-2026-48104
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install 7-zip 2>/dev/null || \
sudo dnf upgrade 7-zip 2>/dev/null || \
sudo yum update 7-zip

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i 7-zip 2>/dev/null || rpm -qa | grep -i 7-zip

# 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.

🔗 Verified Technical References

Authorities
  • No records filed in this category.
Distributions
  • No records filed in this category.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-48104 in 7-zip 7-zip?

Review vendor-specific security notices and update 7-zip 7-zip 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-2026-48104?

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-2026-48104?

CVE-2026-48104 is classified with a CVSS 3.1 Base Score of 4.2 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
4.2
MEDIUM SEVERITY
CVE ID CVE-2026-48104
Weakness CWE-125
Vendor 7-zip
Product 7-zip
Published 2026-06-05
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:L