A vulnerability in the AnyConnect SSL VPN feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to an implementation error within the SSL/TLS session handling process that can prevent the release of a session handler under specific conditions. An attacker could exploit this vulnerability by sending crafted SSL/TLS traffic to an affected device, increasing the probability of session handler leaks. A successful exploit could allow the attacker to eventually deplete the available session handler pool, preventing new sessions from being established and causing a DoS condition.
CVE-2023-20042
This high-severity CVE scores 8.6 under NVD CVSS v3. EPSS exploit probability: 0.7%, top 51% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 8.6
- EG Score
- 8.6(medium)
- EG Risk
- 43(Track)EG Risk 43/100SSVC: 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 computedSeverity86% × 45%Exploitation1% × 40%Automatability30% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 1%
- EPSS %ILE
- 50%
- KEV
- Not listed
Published
November 1, 2023
Last Modified
August 11, 2026
Advisory Details (1)
Auto-updated Aug 11, 2026Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software AnyConnect SSL/TLS VPN Denial of Service Vulnerability
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ssl-dos-kxG8mpUAWeakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 8× in last 7d / 31× 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 157 total refreshes for this CVE.
- 2026-09-07 15:59 UTCEPSS rescore
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- 2026-08-13 21:58 UTCEPSS rescore
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- 2026-08-11 19:57 UTCEG score recompute▲ 1.80
- 2026-08-11 19:57 UTCGHSA enrichment
- 2026-08-11 19:37 UTCNVD updateCVSS v3 → 8.6 · severity → HIGH
- 2026-08-09 13:44 UTCEPSS rescore
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- 2026-07-23 02:18 UTCEG score recompute
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Related CVEs(same CWE)
Same CWE
10 shownCWE-404
- CVE-2018-8639NVD 7.8EG 9.0 KEVEPSS p98CRITICAL
- CVE-2018-8611NVD 7.8EG 9.0 KEVEPSS p90CRITICAL
- CVE-2018-8453NVD 7.8EG 9.0 KEVEPSS p99CRITICAL
- CVE-2018-8406NVD 7.8EG 9.0 KEVCRITICAL
- CVE-2018-8405NVD 7.8EG 9.0 KEVCRITICAL
- CVE-2018-8120NVD 7.0EG 9.0 KEVEPSS p99CRITICAL
- CVE-2017-6627NVD 7.5EG 9.0 KEVEPSS p93CRITICAL
- CVE-2018-8450EG 8.8EPSS p97HIGH
- CVE-2019-1708EG 8.6HIGH
- CVE-2019-1706EG 8.6HIGH
Frequently asked(5)
What is CVE-2023-20042?
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Dependency Blast Radius
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