CVE-2026-0300

CRITICALPre-NVD 9.39.8▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.3 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2026-05-06), indicating real-world exploitation has been confirmed by US federal agencies. the CNA's CVSS baseline 9.3 retained for reference (NVD's own analysis pending). Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, cna:palo_alto, epss, ghsa
Trending — 4 sources updated this weekExploited in the wild
9.3
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS: 32%CVSS: 9.3Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

A buffer overflow vulnerability in the User-ID™ Authentication Portal (aka Captive Portal) service of Palo Alto Networks PAN-OS software allows an unauthenticated attacker to execute arbitrary code with root privileges on the PA-Series and VM-Series firewalls by sending specially crafted packets.

The risk of this issue is greatly reduced if you secure access to the User-ID™ Authentication Portal per the best practice guidelines https://knowledgebase.paloaltonetworks.com/KCSArticleDetail by restricting access to only trusted internal IP addresses.

Prisma Access, Cloud NGFW and Panorama appliances are not impacted by this vulnerability.

CVSS v3
9.3
EG Score
9.8(high)
EPSS
98.1%
KEV
⚠ Exploited

Published

May 6, 2026

Last Modified

July 14, 2026

Advisory Details (2)

Auto-updated May 9, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: cisa.
cisa Patch Available🔴 Active Exploitation

Known Exploited Vulnerabilities Catalog | CISA

Known Exploited Vulnerabilities Catalog | CISA. Listed in CISA Known Exploited Vulnerabilities catalog.

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-0300
generic

CVE-2026-0300 PAN-OS: Unauthenticated user initiated Buffer Overflow Vulnerability in User-ID™ Authentication Portal

https://security.paloaltonetworks.com/CVE-2026-0300

Vendor Advisories for CVE-2026-0300(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 96× in last 7d / 402× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 686 total refreshes for this CVE.

  1. 2026-07-16 08:04 UTCEG score recompute
  2. 2026-07-16 08:03 UTCGHSA enrichment
  3. 2026-07-16 04:09 UTCEG score recompute
  4. 2026-07-16 04:09 UTCGHSA enrichment
  5. 2026-07-16 00:14 UTCEG score recompute
  6. 2026-07-16 00:14 UTCGHSA enrichment
  7. 2026-07-15 20:19 UTCEG score recompute
  8. 2026-07-15 20:19 UTCGHSA enrichment
  9. 2026-07-15 16:57 UTCEPSS rescore
  10. 2026-07-15 16:49 UTCCISA KEV update
  11. 2026-07-15 16:23 UTCEG score recompute
  12. 2026-07-15 16:23 UTCGHSA enrichment
  13. 2026-07-15 15:04 UTCCISA KEV update
  14. 2026-07-15 12:28 UTCEG score recompute
  15. 2026-07-15 12:28 UTCGHSA enrichment
  16. 2026-07-15 08:32 UTCEG score recompute
  17. 2026-07-15 08:32 UTCGHSA enrichment
  18. 2026-07-15 04:36 UTCEG score recompute
  19. 2026-07-15 04:36 UTCGHSA enrichment
  20. 2026-07-15 00:40 UTCEG score recompute
  21. 2026-07-15 00:40 UTCGHSA enrichment
  22. 2026-07-14 20:44 UTCEG score recompute
  23. 2026-07-14 20:44 UTCGHSA enrichment
  24. 2026-07-14 18:05 UTCCISA KEV update
  25. 2026-07-14 16:48 UTCEG score recompute
Show 75 more
  1. 2026-07-14 16:48 UTCGHSA enrichment
  2. 2026-07-14 12:52 UTCEG score recompute
  3. 2026-07-14 12:52 UTCGHSA enrichment
  4. 2026-07-14 08:57 UTCEG score recompute
  5. 2026-07-14 08:57 UTCGHSA enrichment
  6. 2026-07-14 05:02 UTCEG score recompute
  7. 2026-07-14 05:02 UTCGHSA enrichment
  8. 2026-07-14 01:07 UTCEG score recompute
  9. 2026-07-14 01:07 UTCGHSA enrichment
  10. 2026-07-13 21:12 UTCEG score recompute
  11. 2026-07-13 21:12 UTCGHSA enrichment
  12. 2026-07-13 17:16 UTCEG score recompute
  13. 2026-07-13 17:16 UTCGHSA enrichment
  14. 2026-07-13 17:07 UTCCISA KEV update
  15. 2026-07-13 13:20 UTCEG score recompute
  16. 2026-07-13 13:20 UTCGHSA enrichment
  17. 2026-07-13 09:25 UTCEG score recompute
  18. 2026-07-13 09:25 UTCGHSA enrichment
  19. 2026-07-13 06:12 UTCEPSS rescore
  20. 2026-07-13 05:30 UTCEG score recompute
  21. 2026-07-13 05:30 UTCGHSA enrichment
  22. 2026-07-13 01:35 UTCEG score recompute
  23. 2026-07-13 01:34 UTCGHSA enrichment
  24. 2026-07-12 21:40 UTCEG score recompute
  25. 2026-07-12 21:40 UTCGHSA enrichment
  26. 2026-07-12 17:45 UTCEG score recompute
  27. 2026-07-12 17:45 UTCGHSA enrichment
  28. 2026-07-12 13:50 UTCEG score recompute
  29. 2026-07-12 13:50 UTCGHSA enrichment
  30. 2026-07-12 09:54 UTCEG score recompute
  31. 2026-07-12 09:54 UTCGHSA enrichment
  32. 2026-07-12 05:58 UTCEG score recompute
  33. 2026-07-12 05:58 UTCGHSA enrichment
  34. 2026-07-12 05:46 UTCEPSS rescore
  35. 2026-07-12 02:03 UTCEG score recompute
  36. 2026-07-12 02:03 UTCGHSA enrichment
  37. 2026-07-11 22:07 UTCEG score recompute
  38. 2026-07-11 22:07 UTCGHSA enrichment
  39. 2026-07-11 18:12 UTCEG score recompute
  40. 2026-07-11 18:12 UTCGHSA enrichment
  41. 2026-07-11 14:17 UTCEG score recompute
  42. 2026-07-11 14:17 UTCGHSA enrichment
  43. 2026-07-11 10:22 UTCEG score recompute
  44. 2026-07-11 10:22 UTCGHSA enrichment
  45. 2026-07-11 08:27 UTCEPSS rescore
  46. 2026-07-11 06:27 UTCEG score recompute
  47. 2026-07-11 06:27 UTCGHSA enrichment
  48. 2026-07-11 02:32 UTCEG score recompute
  49. 2026-07-11 02:32 UTCGHSA enrichment
  50. 2026-07-10 22:37 UTCEG score recompute
  51. 2026-07-10 22:37 UTCGHSA enrichment
  52. 2026-07-10 18:41 UTCEG score recompute
  53. 2026-07-10 18:41 UTCGHSA enrichment
  54. 2026-07-10 17:52 UTCCISA KEV update
  55. 2026-07-10 14:46 UTCEG score recompute
  56. 2026-07-10 14:46 UTCGHSA enrichment
  57. 2026-07-10 10:51 UTCEG score recompute
  58. 2026-07-10 10:51 UTCGHSA enrichment
  59. 2026-07-10 06:56 UTCEG score recompute
  60. 2026-07-10 06:56 UTCGHSA enrichment
  61. 2026-07-10 03:01 UTCEG score recompute
  62. 2026-07-10 03:01 UTCGHSA enrichment
  63. 2026-07-09 23:05 UTCEG score recompute
  64. 2026-07-09 23:05 UTCGHSA enrichment
  65. 2026-07-09 19:11 UTCEG score recompute
  66. 2026-07-09 19:10 UTCGHSA enrichment
  67. 2026-07-09 19:10 UTCEPSS rescore
  68. 2026-07-09 15:16 UTCEG score recompute
  69. 2026-07-09 15:15 UTCGHSA enrichment
  70. 2026-07-09 11:20 UTCEG score recompute
  71. 2026-07-09 11:20 UTCGHSA enrichment
  72. 2026-07-09 07:25 UTCEG score recompute
  73. 2026-07-09 07:25 UTCGHSA enrichment
  74. 2026-07-09 03:30 UTCEG score recompute
  75. 2026-07-09 03:30 UTCGHSA enrichment

Publicly available exploits

(2 references)

Working exploit code is in the public domain (2 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCp3Nt3st3r-sTAr/CVE-2026-0300-POC
    First seen May 6, 2026
    Open source ↗
  • GitHub PoCqassam-315/PAN-OS-User-ID-Buffer-Overflow-PoC
    First seen May 6, 2026

    A research-grade Proof-of-Concept (PoC) for CVE-2026-0300, targeting the Buffer Overflow vulnerability in Palo Alto Networks PAN-OS User-ID™ Authentication Portal (CWE-787).

    Open source ↗

Related CVEs(same CWE)

Frequently asked(6)

What is CVE-2026-0300?
CVE-2026-0300 is a critical vulnerability published on May 6, 2026. A buffer overflow vulnerability in the User-ID™ Authentication Portal (aka Captive Portal) service of Palo Alto Networks PAN-OS software allows an unauthenticated attacker to execute arbitrary code with root privileges on the PA-Series and VM-Series firewalls by sending specially crafted packets.…
When was CVE-2026-0300 disclosed?
CVE-2026-0300 was first published in the National Vulnerability Database on May 6, 2026, with the most recent update on July 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-0300 actively exploited?
Yes. CISA added CVE-2026-0300 to the Known Exploited Vulnerabilities catalog on May 6, 2026, affecting Palo Alto Networks PAN-OS. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2026-0300?
CVE-2026-0300 has a CVSS v4.0 base score of 9.3 (CNA self-assessment; NVD's own analysis pending). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.8.
Which products are affected by CVE-2026-0300?
CVE-2026-0300 affects Palo Alto Networks PAN-OS. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.
How do I remediate CVE-2026-0300?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-0300, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-0300

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