CVE-2026-20131

CRITICALPre-NVD 10.010.0—
EchelonGraph scoreHIGH confidence

Score elevated to 10.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2026-03-19), indicating real-world exploitation has been confirmed by US federal agencies. the CNA's CVSS baseline 10.0 retained for reference (NVD's own analysis pending). Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, cna:cisco, epss, ghsa
Trending — 4 sources updated this weekExploited in the wild
10.0EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 33%CVSS: 10.0Exploit: cisa kev · ssvc active · kev ransomware · epss top5pct · public exploitExposed: 0

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

A vulnerability in the web-based management interface of Cisco Secure Firewall Management Center (FMC) Software could allow an unauthenticated, remote attacker to execute arbitrary Java code as root on an affected device. This vulnerability is due to insecure deserialization of a user-supplied Java byte stream. An attacker could exploit this vulnerability by sending a crafted serialized Java object to the web-based management interface of an affected device. A successful exploit could allow the attacker to execute arbitrary code on the device and elevate privileges to root. Note: If the FMC management interface does not have public internet access, the attack surface that is associated with this vulnerability is reduced.

CVSS v3
10.0
EG Score
10.0(high)
EG Risk
100(Act)
EG Risk 100/100SSVC: Act

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity100% × 45%
Exploitation100% × 40%
Automatability100% × 15%
Action: Fix now — active exploitation, automatable, high impact.
EPSS PROB
33%
EPSS %ILE
98%
KEV
⚠ Exploited

Published

March 4, 2026

Last Modified

August 14, 2026

Advisory Details (3)

Auto-updated Sep 18, 2026
No patch confirmed yet.
generic

Cisco Secure Firewall Management Center Software Remote Code Execution Vulnerability

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-rce-NKhnULJh
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-2026-20131
generic

Amazon threat intelligence teams identify Interlock ransomware campaign targeting enterprise firewalls | AWS Security Blog

https://aws.amazon.com/blogs/security/amazon-threat-intelligence-teams-identify-interlock-ransomware-campaign-targeting-enterprise-firewalls/

Vendor Advisories for CVE-2026-20131(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 57× in last 7d / 251× 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 462 total refreshes for this CVE.

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

    Originally a Honeypot for CVE-2026-20131

    Open source ↗
  • GitHub PoCsak110/CVE-2026-20131
    First seen Mar 11, 2026
    Open source ↗

Related CVEs(same CWE)

Frequently asked(6)

What is CVE-2026-20131?
CVE-2026-20131 is a critical vulnerability published on March 4, 2026. A vulnerability in the web-based management interface of Cisco Secure Firewall Management Center (FMC) Software could allow an unauthenticated, remote attacker to execute arbitrary Java code as root on an affected device. This vulnerability is due to insecure deserialization of a user-supplied…
When was CVE-2026-20131 disclosed?
CVE-2026-20131 was first published in the National Vulnerability Database on March 4, 2026, with the most recent update on August 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-20131 actively exploited?
Yes. CISA added CVE-2026-20131 to the Known Exploited Vulnerabilities catalog on March 19, 2026, affecting Cisco Secure Firewall Management Center (FMC). KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2026-20131?
CVE-2026-20131 has a CVSS v4.0 base score of 10.0 (CNA self-assessment; NVD's own analysis pending).
Which products are affected by CVE-2026-20131?
CVE-2026-20131 affects Cisco Secure Firewall Management Center (FMC). 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-2026-20131?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-20131, 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-2026-20131

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