Security readout for executives and security teams
Plain-English summary
A privileged attacker can upload a malicious archive to SonicWall NSM On-Prem and cause files to be written outside the intended folder. This could compromise sensitive information, alter systems, or disrupt service. The issue is critical, but the supplied evidence does not establish active exploitation.
Executive priority
Prioritize immediate identification and remediation of affected NSM On-Prem systems, especially externally reachable or broadly administered instances. High privileges reduce opportunistic exposure, but successful exploitation could produce severe cross-system confidentiality, integrity, and availability consequences.
Technical view
CVE-2026-81939 is a remotely reachable Zip Slip path-traversal flaw (CWE-22) in NSM On-Prem file upload and archive processing. A crafted archive can escape the extraction directory. CVSS 3.1 is 9.1: low complexity, high privileges required, no user interaction, changed scope, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is limited to SonicWall Network Security Manager On-Prem 4.3.0 and earlier where an attacker can reach the affected upload workflow and already holds high privileges. The bundle does not identify affected configurations, internet exposure requirements, or cloud-hosted products.
Exploitation context
The supplied record is not listed in KEV and provides no evidence of active exploitation or public exploit availability. Exploitation requires high privileges but is otherwise network-accessible, low-complexity, and needs no additional user interaction. Treat privileged account compromise as an important precursor.
Researcher notes
The record identifies archive path traversal but does not describe affected endpoints, archive formats, filesystem paths, detection indicators, patch version, or root-cause implementation details. Validation should remain non-destructive and focus on versions, access controls, logs, and unexpected filesystem changes. Consult SNWLID-2026-0015 for vendor-specific remediation details.
Mitigation direction
- Inventory NSM On-Prem deployments and identify systems running version 4.3.0 or earlier.
- Review the SonicWall advisory for the vendor-approved fixed release or mitigation.
- Restrict NSM access to trusted administrative networks and authorized personnel.
- Limit or temporarily disable affected archive-upload workflows where operationally feasible.
- Monitor privileged accounts and revoke unnecessary administrative access.
Validation and detection
- Confirm each NSM On-Prem instance and its installed version.
- Verify systems are outside the stated affected range using SonicWall guidance.
- Review privileged account activity around file uploads and archive processing.
- Inspect relevant logs and filesystems for unexpected writes outside intended extraction directories.
- Confirm management interfaces are restricted to approved administrative paths.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-22: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupFile access behavior lookup
The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-81939 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H2.36CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
9.1CriticalVector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2026-0015CVE reference, sonicwall · vendor-advisory
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.