CVE-2026-20004 is a high-severity denial-of-service vulnerability affecting the TLS library in Cisco IOS XE Software, stemming from improper memory management during TLS connection setup. An unauthenticated, adjacent attacker can exploit this with low complexity by repeatedly triggering TLS connection conditions, leading to memory exhaustion and an unexpected device reload. While there is no known active exploitation, public exploit code, or KEV listing, the vulnerability has received limited community discussion and media coverage.
| Vendor | Product | Version(s) | CPE |
|---|---|---|---|
| Cisco | Cisco IOS XE Software | 16.10.1, 16.10.1a, 16.10.1b, 16.10.1c, 16.10.1d, 16.10.1e, 16.10.1f, 16.10.1g, 16.10.1s, 16.10.2, 16.10.3, 16.11.1, 16.11.1a, 16.11.1b, 16.11.1s, 16.11.2, 16.12.1, 16.12.10, 16.12.10a, 16.12.11, 16.12.12, 16.12.13, 16.12.14, 16.12.15, 16.12.1a, 16.12.1c, 16.12.1s, 16.12.1t, 16.12.1w, 16.12.1x, 16.12.1y, 16.12.1z1, 16.12.1z2, 16.12.2, 16.12.2a, 16.12.2s, 16.12.3, 16.12.3a, 16.12.3s, 16.12.4, 16.12.4a, 16.12.5, 16.12.5a, 16.12.5b, 16.12.6, 16.12.6a, 16.12.7, 16.12.8, 16.12.9, 16.9.1, 16.9.1a, 16.9.1b, 16.9.1s, 16.9.2, 16.9.3, 16.9.3a, 16.9.4, 16.9.5, 16.9.5f, 16.9.6, 16.9.7, 16.9.8, 17.1.1, 17.1.1a, 17.1.1s, 17.1.1t, 17.1.3, 17.10.1, 17.10.1a, 17.10.1b, 17.11.1, 17.11.1a, 17.12.1, 17.12.1a, 17.12.1w, 17.12.1x, 17.12.1y, 17.12.1z, 17.12.1z1, 17.12.1z2, 17.12.1z3, 17.12.1z4, 17.12.1z5, 17.12.1z6, 17.12.2, 17.12.2a, 17.12.3, 17.12.3a, 17.12.4, 17.12.4a, 17.12.4b, 17.13.1, 17.13.1a, 17.14.1, 17.14.1a, 17.15.1, 17.15.1a, 17.15.1b, 17.15.1w, 17.15.1x, 17.15.1y, 17.15.1z, 17.16.1, 17.16.1a, 17.2.1, 17.2.1a, 17.2.1r, 17.2.1v, 17.2.2, 17.2.3, 17.3.1, 17.3.1a, 17.3.1w, 17.3.1x, 17.3.1z, 17.3.2, 17.3.2a, 17.3.3, 17.3.4, 17.3.4a, 17.3.4b, 17.3.4c, 17.3.5, 17.3.5a, 17.3.5b, 17.3.6, 17.3.7, 17.3.8, 17.3.8a, 17.4.1, 17.4.1a, 17.4.1b, 17.4.2, 17.4.2a, 17.5.1, 17.5.1a, 17.6.1, 17.6.1a, 17.6.1w, 17.6.1x, 17.6.1y, 17.6.1z, 17.6.1z1, 17.6.2, 17.6.3, 17.6.3a, 17.6.4, 17.6.5, 17.6.5a, 17.6.6, 17.6.6a, 17.6.7, 17.6.8, 17.6.8a, 17.7.1, 17.7.1a, 17.7.1b, 17.7.2, 17.8.1, 17.8.1a, 17.9.1, 17.9.1a, 17.9.1w, 17.9.1x, 17.9.1x1, 17.9.1y, 17.9.1y1, 17.9.2, 17.9.2a, 17.9.3, 17.9.3a, 17.9.4, 17.9.4a, 17.9.5, 17.9.5a, 17.9.5b, 17.9.5e, 17.9.5f, 17.9.6, 17.9.6aCNA affected |
CVSS version used by this source: 3.1
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.
The average CVE in this peer group has 0.2 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.
Cisco IOS XE Software TLS Memory Exhaustion Denial of Service Vulnerability
Mar 25, 2026Cisco IOS XE Software TLS Memory Exhaustion Denial of Service Vulnerability
Mar 25, 2026Cisco IOS XE Software TLS Memory Exhaustion Denial of Service Vulnerability
Mar 25, 2026