CVE-2026-20248

MEDIUMPre-NVD 6.86.8—
EchelonGraph scoreHIGH confidence

Score 6.8 from GitHub Security Advisory published 2026-09-16. the CNA's CVSS baseline 6.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:cisco, epss, ghsa
Trending — 4 sources updated this week
6.8EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.8Exploit: 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 DNS over TCP implementation of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the TCP DNS response handler to unexpectedly restart, causing the device to reload. This vulnerability is due to a logic error when parsing a DNS query and tracking the size of the incoming buffers. An attacker could exploit this vulnerability by formatting a crafted reply to a DNS query sent from the targeted device. A successful exploit could allow the attacker to cause the device to reload, causing a denial of service (DoS) condition. Note: The attacker must be able to respond to DNS queries from the device, either by controlling the DNS service or through a machine-in-the-middle attack.

CVSS v3
6.8
EG Score
6.8(high)
EG Risk
31(Track)
EG Risk 31/100SSVC: 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
Severity68% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
28%
KEV
Not listed

Published

September 16, 2026

Last Modified

September 18, 2026

Advisory Details (1)

Auto-updated Sep 16, 2026
No patch confirmed yet.
generic

Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software TCP DNS Denial of Service Vulnerability

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-tcpdns-dos-p6dUnjr5

Vendor Advisories for CVE-2026-20248(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 12× in last 7d / 12× 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. 2026-09-18 19:27 UTCEPSS rescore
  2. 2026-09-18 19:20 UTCEG score recompute
  3. 2026-09-18 19:20 UTCGHSA enrichment
  4. 2026-09-18 13:41 UTCEG score recompute
  5. 2026-09-18 13:41 UTCGHSA enrichment
  6. 2026-09-17 14:25 UTCEG score recompute
  7. 2026-09-17 14:25 UTCGHSA enrichment
  8. 2026-09-17 13:52 UTCEG score recompute
  9. 2026-09-17 13:52 UTCGHSA enrichment
  10. 2026-09-16 21:26 UTCEG score recompute
  11. 2026-09-16 20:34 UTCEG score recompute
  12. 2026-09-16 20:29 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-20248?
CVE-2026-20248 is a medium vulnerability published on September 16, 2026. A vulnerability in the DNS over TCP implementation of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the TCP DNS response handler to unexpectedly restart, causing…
When was CVE-2026-20248 disclosed?
CVE-2026-20248 was first published in the National Vulnerability Database on September 16, 2026, with the most recent update on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-20248 actively exploited?
CVE-2026-20248 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 72.5% of all scored CVEs.
What is the CVSS score of CVE-2026-20248?
CVE-2026-20248 has a CVSS v4.0 base score of 6.8 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-20248?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-20248, 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-2026-20248

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