CriticalCVE-2024-3393

    PAN-OS: Firewall Denial of Service (DoS) in DNS Security Using a Specially Crafted Packet (CVE-2024-3393)

    Published In CISA KEV since Sources: pwn.watch, CVE.org

    What is affected, what to do

    The vulnerability in Palo Alto Networks PAN-OS allows an unauthenticated attacker to remotely reboot the firewall by sending a malicious DNS packet through the data plane. This results in a Denial of Service, as repeated attempts will put the firewall into maintenance mode. The vulnerability is actively exploited in the wild and was added to the CISA KEV list on December 30, 2024. All PAN-OS versions with the DNS Security feature are affected. Immediate patching to the latest version is critical to maintain security.

    The vulnerability is being actively exploited; treat it as a priority. Update Palo Alto Networks PAN-OS to version 11.2.3, Palo Alto Networks PAN-OS to version 11.1.2-h16, Palo Alto Networks PAN-OS to version 10.2.8-h19. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Palo Alto Networks PAN-OS lt 11.2.0..11.2.3
    • Palo Alto Networks PAN-OS lt 11.1.0..11.1.2-h16
    • Palo Alto Networks PAN-OS lt 10.2.8..10.2.8-h19
    • Palo Alto Networks PAN-OS lt 10.1.14..10.1.14-h8
    Fixed in
    • Palo Alto Networks PAN-OS 11.2.3
    • Palo Alto Networks PAN-OS 11.1.2-h16
    • Palo Alto Networks PAN-OS 10.2.8-h19
    • Palo Alto Networks PAN-OS 10.1.14-h8

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    8.7

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v4

    7.5

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: pwn.watch, CVE.org

    29.1 %

    EPSS score

    Elevated — model estimates 10-50% exploitation likelihood.

    Source: FIRST EPSS, percentile 98.2

    Show all metrics
    Severity
    Critical
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    227.95 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    actively exploited
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    8.7 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    7.5
    CVSS v4

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    8.7
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    29.1 %
    Elevated — model estimates 10-50% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    98.2
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    Actively exploited
    Published
    In CISA KEV since

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-754

    Response and mitigation

    Why act now?

    Prioritisation rationale

    The bug is triggerable over the network without authentication and needs only a single crafted DNS packet traversing the data plane. The result is a complete loss of firewall availability, escalating to maintenance mode that requires hands-on console recovery. Confidentiality and integrity are not affected, and CISA does not flag ransomware use, yet the exploitation likelihood is very high and attackers have caused real-world crashes of perimeter firewalls. If your internet edge or OT/KRITIS segmentation depends on PAN-OS with DNS Security logging enabled, rate this high/urgent and apply the workaround the same day. Units without the DNS Security licence or with logging off can follow the normal patch cycle.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Confirm exposure: Only firewalls with an active DNS Security licence and DNS Security logging enabled in an Anti-Spyware profile are exploitable. Pull the PAN-OS version of every firewall, for example via show system info | match sw-version or Panorama. Then identify which Anti-Spyware profiles with DNS Security categories are attached to security rules.
      • Patch: Upgrade affected units to 10.1.14-h8, 10.2.8-h19, 11.1.2-h16 or 11.2.3 or later. Fixes for other maintenance trains (e.g. 10.2.9+, 11.1.3+) are available from the vendor; look up the exact version in the vendor advisory. Patch internet-facing perimeter gateways first.
      • Interim workaround if you cannot patch within hours: Under Objects > Security Profiles > Anti-Spyware > DNS Policies > DNS Security, set Log Severity to none for every DNS Security category. Commit and push the change through Panorama to all device groups. Revert the setting once patched.
      • Prepare for maintenance mode: Repeated triggering drops the box into maintenance mode. Make sure out-of-band console access (serial, terminal server, IPMI) and a recovery runbook are ready and tested for every critical firewall. Keep a current running-config.xml backup in the emergency kit.
      • Check HA state: Confirm both nodes of each HA pair are patched or carry the workaround. An unprotected peer will crash the same way after failover.

    2. Runbook step 2

      Mitigation layers

      • Configuration (most effective): Disable DNS Security logging as described above. Alternatively, temporarily detach the DNS Security profile from policy. That removes sinkholing and DNS-tunnelling detection, so it is a deliberate risk trade-off. Record the decision in the risk register.
      • Network segmentation / DNS architecture: Allow client DNS (UDP/TCP 53) only to internal resolvers and block direct queries to external name servers. This shrinks the number of DNS flows crossing the data plane and makes targeted triggering from inside harder. It does not fully stop delivery via resolver responses.
      • Resilience: Run HA pairs with link and path monitoring. For critical-infrastructure chokepoints, agree a fail-closed or bypass plan with network operations so that a reboot loop never results in uninspected traffic.
      • IAM / management plane: The flaw sits in the data plane, not the management interface. Still, restrict management (HTTPS/443, SSH/22) to dedicated admin networks so that recovery work is not exposed to concurrent attacks on PAN-OS.
      • Change management: An emergency change for patch or workaround is justified under NIS2 risk-management duties. Log before/after versions and timestamps.

    3. Runbook step 3

      Detection rules

      • PAN-OS system log (syslog to SIEM): Alert on unexpected reboots and dataplane restarts, i.e. general/ha events with descriptions containing "restart", "reboot", "dataplane down" or "maintenance mode". Example SPL: index=pan sourcetype=pan:system (description="*restart*" OR description="*maintenance*") | stats count by host.
      • Availability telemetry: Correlate SNMP sysUpTime/hrSystemUptime resets, HA failover events and monitoring outages (ICMP, path monitoring). Treat more than one reboot in 24 h without a change ticket as an incident.
      • PAN-OS threat/DNS logs: In the minutes before a reboot, look for DNS Security entries with unusual domains, oversized labels or abnormal response sizes. Preserve source and destination IPs of the last DNS flows before the crash, plus threat-log PCAPs where enabled.
      • Network telemetry (Zeek/Suricata in front of or behind the firewall): Hunt weird.log for malformed DNS (DNS_truncated_*, dns_unmatched_reply) and for repeated queries to the same external domain just before outage times. Enable Suricata DNS anomaly rules (app-layer-event:dns.*).
      • Post-crash forensics: Check show system files for new core dumps from dataplane processes. Collect a tech-support file for vendor support before rebooting or re-imaging.

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    A Denial of Service vulnerability in the DNS Security feature of Palo Alto Networks PAN-OS software allows an unauthenticated attacker to send a malicious packet through the data plane of the firewall that reboots the firewall. Repeated attempts to trigger this condition will cause the firewall to enter maintenance mode.

    Source: pwn.watch, NVD (NIST), cvelistv5, CISA KEV Catalog, CVE.org (MITRE)

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    paloaltonetworksprisma_access
    • —
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Otherpaloaltonetworkspan-os10.1
    Otherpaloaltonetworkspan-os10.1.14
    Otherpaloaltonetworkspan-os10.2
    Otherpaloaltonetworkspan-os10.2.10
    Otherpaloaltonetworkspan-os10.2.11
    Otherpaloaltonetworkspan-os10.2.12
    Otherpaloaltonetworkspan-os10.2.13
    Otherpaloaltonetworkspan-os10.2.8
    Otherpaloaltonetworkspan-os10.2.9
    Otherpaloaltonetworkspan-os11.1
    Otherpaloaltonetworkspan-os11.1.0
    Otherpaloaltonetworkspan-os11.1.1
    Otherpaloaltonetworkspan-os11.1.2
    Otherpaloaltonetworkspan-os11.1.3
    Otherpaloaltonetworkspan-os11.1.4
    Otherpaloaltonetworkspan-os11.2
    Otherpaloaltonetworkspan-os11.2.0
    Otherpaloaltonetworkspan-os11.2.1
    Otherpaloaltonetworkspan-os11.2.2
    Otherpaloaltonetworkspan-os—
    Operating systemPalo Alto NetworksPAN-OS11.2.2

    Weakness classes (CWE)

    • CWE-754Improper Check for Unusual or Exceptional Conditions

      Class

      The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.

      Entry at MITRE CWE-754

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited

    References & sources

    • security.paloaltonetworks.comPalo Alto Networks advisory: CVE-2024-3393Vendor advisory, Vendor advisory, pwn-watch
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2024-3393government-resource, US government resource
    • pwn.watchpwn.watch: Palo Alto Networks PAN-OS Malicious DNS Packetpwn-watch
    • NVD (NIST)NVD: CVE-2024-3393pwn-watch
    • cisa.govCISA Known Exploited Vulnerabilities Catalogpwn-watch
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