Security readout for executives and security teams
Plain-English summary
This flaw lets a logged-in attacker target Palo Alto Networks GlobalProtect Clientless VPN during SAML authentication and run code as root. That means full compromise of the affected firewall or service component is possible if exposed and vulnerable.
Executive priority
Treat this as high priority for exposed VPN infrastructure because successful exploitation could give root-level control of a security boundary device. Absence from KEV lowers evidence of current exploitation, not technical severity.
Technical view
CVE-2021-3056 is a PAN-OS memory corruption vulnerability in GlobalProtect Clientless VPN during SAML authentication. The CVSS 3.1 score is 8.8 with network attack vector, low complexity, low privileges required, no user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most likely where GlobalProtect Clientless VPN with SAML authentication is enabled on affected PAN-OS versions before the fixed releases, or on impacted Prisma Access 2.1 Preferred firewalls.
Exploitation context
The bundle does not identify active exploitation, and KEV is false. Exploitation requires an authenticated attacker and the vulnerable GlobalProtect Clientless VPN SAML authentication path to be reachable.
Researcher notes
The affected path is specifically GlobalProtect Clientless VPN during SAML authentication, with CWE-120 memory corruption characteristics. The source bundle supports authenticated remote code execution as root but does not provide exploit telemetry or detailed remediation for all Prisma Access versions listed.
Mitigation direction
- Upgrade PAN-OS to 8.1.20, 9.0.14, 9.1.9, 10.0.1, or later as applicable.
- For Prisma Access, check Palo Alto Networks guidance for impacted 2.1 Preferred firewalls.
- Prioritize systems exposing GlobalProtect Clientless VPN with SAML authentication.
- Review vendor advisory for branch-specific upgrade constraints before scheduling remediation.
Validation and detection
- Inventory PAN-OS versions across internet-facing and partner-facing firewall portals.
- Confirm whether GlobalProtect Clientless VPN and SAML authentication are enabled.
- Check Prisma Access deployments for 2.1 Preferred firewall exposure.
- Verify upgraded systems report fixed or later PAN-OS versions.
- Review authentication and system logs for unusual authenticated SAML activity.
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-120: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-3056 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
- High
- CVSS
- 8.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/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.
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:L/UI:N/S:U/C:H/I:H/A:H2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://security.paloaltonetworks.com/CVE-2021-3056CVE reference · x_refsource_MISC
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.
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.