CVE-2026-20301

HIGHPre-NVD 8.68.6—
EchelonGraph scoreHIGH confidence

Score 8.6 from GitHub Security Advisory (severity: HIGH) published 2026-08-05. a secondary CVSS source baseline 8.6; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
8.6EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.6Exploit: None knownExposed: 0

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

A vulnerability in the Extensible Messaging Client Protocol (XMCP), also referred to as the External Client protocol, of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper handling of malformed XMCP packets. An attacker could exploit this vulnerability by sending a malformed XMCP packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload unexpectedly, resulting in a DoS condition. The attacker does not need the XMCP client username to exploit this vulnerability.

CVSS v3
8.6
EG Score
8.6(high)
EG Risk
54(Track)
EG Risk 54/100SSVC: Track

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
Severity86% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
26%
KEV
Not listed

Published

August 5, 2026

Last Modified

August 6, 2026

Advisory Details (1)

Auto-updated Aug 5, 2026
No patch confirmed yet.
generic

Cisco IOS Software and IOS XE Software Extensible Messaging Client Protocol Denial of Service Vulnerability

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-xmcp-thbAr34t

Vendor Advisories for CVE-2026-20301(2)

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 29× in last 7d / 68× 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.

  1. 2026-08-21 07:26 UTCEG score recompute
  2. 2026-08-21 07:26 UTCGHSA enrichment
  3. 2026-08-20 22:55 UTCEPSS rescore
  4. 2026-08-20 20:06 UTCGHSA enrichment
  5. 2026-08-20 08:47 UTCGHSA enrichment
  6. 2026-08-19 21:27 UTCEG score recompute
  7. 2026-08-19 21:27 UTCGHSA enrichment
  8. 2026-08-19 17:03 UTCEPSS rescore
  9. 2026-08-19 10:03 UTCGHSA enrichment
  10. 2026-08-18 22:37 UTCEG score recompute
  11. 2026-08-18 22:36 UTCGHSA enrichment
  12. 2026-08-18 13:48 UTCEPSS rescore
  13. 2026-08-18 11:15 UTCGHSA enrichment
  14. 2026-08-17 23:51 UTCEG score recompute
  15. 2026-08-17 23:51 UTCGHSA enrichment
  16. 2026-08-17 13:47 UTCEPSS rescore
  17. 2026-08-17 12:31 UTCGHSA enrichment
  18. 2026-08-17 01:12 UTCEG score recompute
  19. 2026-08-17 01:12 UTCGHSA enrichment
  20. 2026-08-16 14:56 UTCEPSS rescore
  21. 2026-08-16 13:52 UTCGHSA enrichment
  22. 2026-08-16 02:33 UTCEG score recompute
  23. 2026-08-16 02:33 UTCGHSA enrichment
  24. 2026-08-16 02:14 UTCEPSS rescore
  25. 2026-08-15 15:14 UTCGHSA enrichment
Show 43 more
  1. 2026-08-15 03:55 UTCEG score recompute
  2. 2026-08-15 03:55 UTCGHSA enrichment
  3. 2026-08-15 01:30 UTCEPSS rescore
  4. 2026-08-14 16:35 UTCGHSA enrichment
  5. 2026-08-14 05:14 UTCEG score recompute
  6. 2026-08-14 05:14 UTCGHSA enrichment
  7. 2026-08-13 22:00 UTCEPSS rescore
  8. 2026-08-13 17:54 UTCGHSA enrichment
  9. 2026-08-13 06:35 UTCGHSA enrichment
  10. 2026-08-12 19:15 UTCEG score recompute
  11. 2026-08-12 19:15 UTCGHSA enrichment
  12. 2026-08-12 13:50 UTCEPSS rescore
  13. 2026-08-12 07:56 UTCGHSA enrichment
  14. 2026-08-11 20:37 UTCEG score recompute
  15. 2026-08-11 20:37 UTCGHSA enrichment
  16. 2026-08-11 13:42 UTCEPSS rescore
  17. 2026-08-11 09:18 UTCEG score recompute
  18. 2026-08-11 09:18 UTCGHSA enrichment
  19. 2026-08-11 00:00 UTCEPSS rescore
  20. 2026-08-10 21:59 UTCGHSA enrichment
  21. 2026-08-10 10:39 UTCGHSA enrichment
  22. 2026-08-09 23:20 UTCEG score recompute
  23. 2026-08-09 23:20 UTCGHSA enrichment
  24. 2026-08-09 13:46 UTCEPSS rescore
  25. 2026-08-09 12:01 UTCGHSA enrichment
  26. 2026-08-09 00:41 UTCEG score recompute
  27. 2026-08-09 00:41 UTCGHSA enrichment
  28. 2026-08-08 16:37 UTCEPSS rescore
  29. 2026-08-08 13:22 UTCGHSA enrichment
  30. 2026-08-08 02:02 UTCEG score recompute
  31. 2026-08-08 02:02 UTCGHSA enrichment
  32. 2026-08-07 14:43 UTCGHSA enrichment
  33. 2026-08-07 03:24 UTCGHSA enrichment
  34. 2026-08-06 16:05 UTCEG score recompute
  35. 2026-08-06 16:05 UTCGHSA enrichment
  36. 2026-08-06 13:46 UTCEPSS rescore
  37. 2026-08-06 05:50 UTCGHSA enrichment
  38. 2026-08-05 18:31 UTCEG score recompute
  39. 2026-08-05 18:31 UTCGHSA enrichment
  40. 2026-08-05 17:57 UTCEG score recompute
  41. 2026-08-05 17:30 UTCEG score recompute
  42. 2026-08-05 16:51 UTCEG score recompute
  43. 2026-08-05 16:50 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-20301?
CVE-2026-20301 is a high vulnerability published on August 5, 2026. A vulnerability in the Extensible Messaging Client Protocol (XMCP), also referred to as the External Client protocol, of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This…
When was CVE-2026-20301 disclosed?
CVE-2026-20301 was first published in the National Vulnerability Database on August 5, 2026, with the most recent update on August 6, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-20301 actively exploited?
CVE-2026-20301 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 74.2% of all scored CVEs.
What is the CVSS score of CVE-2026-20301?
CVE-2026-20301 has a CVSS v3 base score of 8.6 (NVD).
How do I remediate CVE-2026-20301?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-20301, 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-2026-20301

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