CVE-2026-0300

CRITICALPre-NVD 9.39.8▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.8 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 58× in last 7d / 227× 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 453 total refreshes for this CVE.

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

Explore →

Is Your Infrastructure Affected by CVE-2026-0300?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs