CVE-2026-20004

highpriority · track · 0EPSS 0.002 · 8 %ileDEEUNLRUUS
grimoire priorityP2 · Scheduled
Exploitable?
—
no known exploitation
Likely / severe?
0.19% (8th) EPSS
CVSS 7.4 · high
Is it mine?
770 products
Check your exposure
Who says so?
6 sources
cnnvd · enisa_euvd · fstec_bdu · cisco_csaf

EPSS · scored 2026-10-27

A vulnerability in the TLS library of Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to exhaust the available memory of an affected device. This vulnerability is due to improper management of memory resources during TLS connection setup. An attacker could exploit this vulnerability by repeatedly triggering the conditions that cause the memory increase. This could be done in a variety of ways, such as by repeatedly attempting Extensible Authentication Protocol (EAP) authentication when local EAP is enabled on an affected device or by using a machine-in-the-middle attack and resetting TLS connections between the affected device and other devices. A successful exploit could allow the attacker to exhaust the available memory on an affected device, resulting in an unexpected reload and a denial of service (DoS) condition.

01

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

02

cvss

Technical severity, 0–10. One row per scoring source.

7.4
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.8–7.4

v3.17.4highAV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · FSTEC (BDU) RU
v3.17.4highCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · ENISA EU
v3.17.4highCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · psirt@cisco.com USexploitability 2.8 · impact 4
v3.16.8mediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)
v3.17.4highCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · NCSC-NL NL
v3.17.4highCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · Cisco PSIRT US
03

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Trackcoordinatorcisa_ssvcUS
04

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-771USCWE-771USCWE-771US
05

affected products (770)

Products and version ranges known to be affected.

showing 20 of 770
06

advisories (3)

Vendor and ecosystem advisories describing this.

  • NCSC-2026-0104Kwetsbaarheden verholpen in Cisco IOS XE SoftwareNL2026-03-26csaf · ncsc_nlNL

    Cisco heeft kwetsbaarheden verholpen in Cisco IOS XE Software, specifiek voor verschillende producten zoals Catalyst 9000 Series Switches, Catalyst CW9800 Family, en Cisco Meraki.

  • WID-SEC-W-2026-0874Cisco IOS und IOS XE Software: Mehrere SchwachstellenDeutsch2026-03-25csaf · cert_bundDE

    Ein Angreifer kann mehrere Schwachstellen in Cisco IOS XE, Cisco IOS und Cisco Catalyst ausnutzen, um sich erweiterte Rechte zu verschaffen, beliebigen Code auszuführen, Sicherheitsmaßnahmen zu umgehen, Cross-Site-Scripting-Angriffe durchzuführen, Daten zu manipulieren, vertrauliche Informationen offenzulegen und einen Denial-of-Service-Zustand herbeizuführen.

  • cisco-sa-iosxe-tls-dos-TVgLDEZLCisco IOS XE Software TLS Memory Exhaustion Denial of Service Vulnerability2026-03-25csaf · cisco_csafUS

    A vulnerability in the TLS library of Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to exhaust the available memory of an affected device. This vulnerability is due to improper management of memory resources during TLS connection setup. An attacker could exploit this vulnerability by repeatedly triggering the conditions that cause the memory increase. This could be done in a variety of ways, such as by repeatedly attempting Extensible Authentication Protocol (EAP) authentication when local EAP is enabled on an affected device or by using a machine-in-the-middle attack and resetting TLS connections between the affected device and other devices. A successful exploit could allow the attacker to exhaust the available memory on an affected device, resulting in an unexpected reload and a denial of service (DoS) condition. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is part of the March 2026 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: March 2026 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication ["https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-75297"].

07

also known as (4)

Other names and identifiers for this entity.

08

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bducisco_csafncsc_nlcert_bundNVDCVE.orgMITRE
published 2026-03-25modified 2026-06-17
09

references (4)

External citations — patches, advisories, analysis.

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