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CVE Record

CVE-2021-3048: PAN-OS: Invalid URLs in an External Dynamic List (EDL) can Lead to Firewall Outage

Certain invalid URL entries contained in an External Dynamic List (EDL) cause the Device Server daemon (devsrvr) to stop responding. This condition causes subsequent commits on the firewall to fail and prevents administrators from performing commits and configuration changes even though the firewall remains otherwise functional. If the firewall then restarts, it results in a denial-of-service (DoS) condition and the firewall stops processing traffic. This issue impacts: PAN-OS 9.0 versions earlier than PAN-OS 9.0.14; PAN-OS 9.1 versions earlier than PAN-OS 9.1.9; PAN-OS 10.0 versions earlier than PAN-OS 10.0.5. PAN-OS 8.1 and PAN-OS 10.1 versions are not impacted.

MediumCVSS 5.9Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This vulnerability can make affected Palo Alto Networks firewalls unable to accept configuration commits when malformed URLs appear in an External Dynamic List. The firewall may keep running, but a later restart can turn the problem into a traffic-impacting outage.

Executive priority

Prioritize remediation for firewalls that depend on frequent policy changes or protect critical traffic paths. This is not described as exploited, but the outage path can affect business continuity if a vulnerable firewall restarts.

Technical view

Affected PAN-OS releases mishandle certain invalid URL entries in an EDL, causing the Device Server daemon devsrvr to stop responding. Commits then fail, preventing configuration changes. After a firewall restart, the source states the device can stop processing traffic, producing denial of service.

Likely exposure

Exposure is most likely on PAN-OS 9.0 before 9.0.14, 9.1 before 9.1.9, or 10.0 before 10.0.5 where URL-based EDLs are used. The source states PAN-OS 8.1 and 10.1 are not impacted.

Exploitation context

The CVSS vector is network-accessible but high complexity, with no privileges or user interaction required. The bundle has no KEV listing and provides no cited evidence of active exploitation, so active exploitation should not be assumed.

Researcher notes

This is CWE-20 input validation leading to availability impact. The key exposure condition is malformed EDL URL content on specific PAN-OS branches. Note the supplied vendor URL references CVE-2020-3048 while the record analyzed is CVE-2021-3048.

Mitigation direction

  • Upgrade PAN-OS 9.0 to 9.0.14 or later.
  • Upgrade PAN-OS 9.1 to 9.1.9 or later.
  • Upgrade PAN-OS 10.0 to 10.0.5 or later.
  • Validate EDL URL entries and remove malformed entries.
  • Check Palo Alto Networks guidance before operational changes.

Validation and detection

  • Inventory PAN-OS versions across affected firewall fleets.
  • Identify firewalls using External Dynamic Lists with URL entries.
  • Confirm affected systems are upgraded to fixed versions.
  • Review logs for devsrvr issues and failed commits.
  • Avoid unnecessary restarts until affected systems are remediated.
Prepared
Confidence
high
Sources
3

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-20: Exact CWE lookup

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cve · low confidence lookup

CVE-2021-3048 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.9 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Official CVE source material

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.

1CVSS vectors
0Timeline events
0ADP providers
2Source links

CVSS vector scores

1 official score

We 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.

ScoreVersionSeverityVectorExploitImpactSource
5.9CVSS 3.1MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H2.23.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

5.9Medium
CVSS 3.1 vector shape for CVE-2021-3048Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Palo Alto NetworksPAN-OS10.1.*, 8.1.*, 9.0, 9.1, 10.0Listed
Weakness

CWE details

CWE-20

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.