CVE-2025-20271

highpriority · track · 0EPSS 0.005 · 45 %ileDEEUNLRUUS

grimoire priorityP2 · Scheduled

Exploitable?

—

no known exploitation

Likely / severe?

0.54% (45th) EPSS

CVSS 8.6 · high

Is it mine?

16 products

Check your exposure

Who says so?

6 sources

cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

A vulnerability in the Cisco AnyConnect VPN server of Cisco Meraki MX and Cisco Meraki Z Series Teleworker Gateway devices could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition in the Cisco AnyConnect service on an affected device. This vulnerability is due to variable initialization errors when an SSL VPN session is established. An attacker could exploit this vulnerability by sending a sequence of crafted HTTPS requests to an affected device. A successful exploit could allow the attacker to cause the Cisco AnyConnect VPN server to restart, resulting in the failure of all established SSL VPN sessions and forcing remote users to initiate a new VPN connection and re-authenticate. A sustained attack could prevent new SSL VPN connections from being established, effectively making the Cisco AnyConnect VPN service unavailable for all legitimate users.

remediations

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

A vendor fix is available.

FixedCisco Meraki MX Firmwarecisco_csaf
Cisco has released software updates that address this vulnerability.
https://software.cisco.com

cvss

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

8.6

010

base score 0–10 · higher = more severe · hover a vector to decode

v3.18.6highAV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · FSTEC (BDU) RU

v3.18.6highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · ENISA EU

v3.18.6highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · psirt@cisco.com USexploitability 3.9 · impact 4

v3.17.9highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)

v3.18.6highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · NCSC-NL NL

v3.18.6highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · Cisco PSIRT US

ssvc

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

Exploitation: none · Automatable: yes · Technical Impact: partialcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-457USCWE-457USCWE-457US

affected products (16)

Products and version ranges known to be affected.

Cisco Meraki MX <18.107.13all versionscert_bundDE
Cisco Meraki MX <18.211.6all versionscert_bundDE
Cisco Meraki MX <19.1.8all versionscert_bundDE
Cisco Meraki MX< 18.107.13cert_bundDE
Cisco Meraki MX< 18.211.6cert_bundDE
Cisco Meraki MX< 19.1.8cert_bundDE
Cisco Cisco Meraki MX Firmwareall versionscisco_csafUS
Cisco Cisco Meraki MX Firmware≤ N/Aenisa_euvdEU
Cisco Systems Inc. Cisco Meraki MX≤ 17fstec_bduRU
Cisco Systems Inc. Cisco Meraki MX≤ 16.2fstec_bduRU
Cisco Systems Inc. Cisco Meraki MX≤ 19.1.8fstec_bduRU
Cisco Systems Inc. Cisco Meraki MX≤ 18.211.6fstec_bduRU
Cisco Systems Inc. Cisco Meraki MX≤ 18.107.13fstec_bduRU
Meraki MX≤ vers:unknown/unknownncsc_nlNLcpe:2.3:h:cisco:meraki_mx:-:*:*:*:*:*:*:*
Cisco Cisco Meraki MX Firmware≤ vers:unknown/n/ancsc_nlNL
Cisco Meraki Z1≤ vers:unknown/unknownncsc_nlNL

advisories (3)

Vendor and ecosystem advisories describing this.

NCSC-2025-0199Kwetsbaarheid verholpen in Cisco AnyConnect VPN voor Meraki MX en ZNL2025-06-19csaf · ncsc_nlNL
Cisco heeft een kwetsbaarheid verholpen in de Cisco AnyConnect VPN server op Cisco Meraki MX en Z Series apparaten.
WID-SEC-W-2025-1361Cisco Meraki MX: Schwachstelle ermöglicht Denial of ServiceDeutsch2025-06-19csaf · cert_bundDE
Ein entfernter, anonymer Angreifer kann eine Schwachstelle in Cisco Meraki MX ausnutzen, um einen Denial of Service Angriff durchzuführen.
cisco-sa-meraki-mx-vpn-dos-sM5GCfm7Cisco Meraki MX and Z Series AnyConnect VPN with Client Certificate Authentication Denial of Service Vulnerability2025-06-18csaf · cisco_csafUS
A vulnerability in the Cisco AnyConnect VPN server of Cisco Meraki MX and Cisco Meraki Z Series Teleworker Gateway devices could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition in the Cisco AnyConnect service on an affected device. This vulnerability is due to variable initialization errors when an SSL VPN session is established. An attacker could exploit this vulnerability by sending a sequence of crafted HTTPS requests to an affected device. A successful exploit could allow the attacker to cause the Cisco AnyConnect VPN server to restart, resulting in the failure of all established SSL VPN sessions and forcing remote users to initiate a new VPN connection and re-authenticate. A sustained attack could prevent new SSL VPN connections from being established, effectively making the Cisco AnyConnect VPN service unavailable for all legitimate users. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu cert_bund cisco_csaf ncsc_nl NVD CVE.org MITRE

published 2025-06-18modified 2026-06-17

references (4)

External citations — patches, advisories, analysis.

scry

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