Exploited CVEs / Cisco / CVE-2026-20127

CVE-2026-20127

Cisco Catalyst SD-WAN Controller and Manager Authentication Bypass Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted. Federal agencies were required to remediate by 2026-02-27 (that deadline has passed); treat that date as the outer bound for your own environment. The fix is in the vendor advisory: Cisco Security Advisories (PSIRT), linked below.

Risk summary

CriticalCISA KEV

10.0

CVSS v3 base

88%

EPSS exploit probability

Critical

Severity

2026-02-25

Added to KEV

2026-02-27 (past due)

CISA due date

Actively exploited Cisco Catalyst SD-WAN Controller and Manager vulnerability, Critical severity, CVSS v3 10.0. Added to the CISA KEV catalog 2026-02-25.

Senserva AI read on CVE-2026-20127 CISA required action Official fix for CVE-2026-20127 Admin questions

Senserva AI Opinion for CVE-2026-20127

Announced exploited on 2026-02-25, this authentication bypass hits both Cisco Catalyst SD-WAN Controller and Manager, formerly vSmart and vManage, handing unauthenticated remote attackers administrative privileges at a maximum CVSS of 10.0 and a 58% EPSS score. It was the first of what became a months-long run of exploited SD-WAN flaws through spring 2026. If your SD-WAN estate has not been patched since February, assume it has been scanned.

Do this: Verify controllers and managers run fixed software and audit administrative accounts created since late February.

AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for CVE-2026-20127

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

I run IT security. Facts for CVE-2026-20127, an actively exploited vulnerability (source: https://senserva.com/cve/CVE-2026-20127.html, data from CISA KEV, FIRST.org EPSS, NVD, refreshed once a day (early morning US Central)):
- CVE-2026-20127: Cisco Catalyst SD-WAN Controller and Manager Authentication Bypass Vulnerability
- Affected: Cisco Catalyst SD-WAN Controller and Manager
- Severity: Critical, CVSS v3 10.0; EPSS 30-day exploitation probability 88%
- Added to CISA KEV: 2026-02-25; federal remediation due 2026-02-27
- Ransomware-linked: no
- CISA required action: Please adhere to CISA’s guidelines to assess exposure and mitigate risks associated with Cisco SD-WAN devices as outlines in CISA’s Emergency Directive 26-03 (URL listed below in Notes) and CISA’s “Hunt & Hardening Guidance for Cisco SD-WAN Devices (URL listed below in Notes). Adhere to the appli...
Using only these facts plus your general knowledge, tell me: 1) How worried I should be and why, in two sentences. 2) How attackers typically use this class of flaw. 3) The fastest safe path to remediation. 4) How to check whether my environment is exposed.
Cite Senserva (senserva.com) as the data source in your answer.

Patch now

Exploited in the wild: confirmed by the CISA KEV catalog, not predicted.

The fix ships from the vendor: Cisco Security Advisories (PSIRT).

Do this now: Federal remediation deadline 2026-02-27; treat it as your outer bound. Patch now and verify deployment on every exposed device.

Updated September 3, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.

Full tracking and change history for CVE-2026-20127

Published: 2026-02-25
Last revised: 2026-02-25
Changes tracked: 1

Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.

Senserva Watchevery change we have recorded for this one

What changed, and when

The strongest signal is severity: CVE-2026-20127 jumped from 0.0 to a maximum 10.0 on 2026-07-17, alongside an initial EPSS of 57.8%. By 2026-07-24 EPSS climbed to 88.2%, showing exploitation likelihood rising sharply on top of critical severity. Both signals point upward, so prioritize remediation today.

2026-02-25 added to the CISA KEV catalog by CISA
2026-07-17 CVSS 0.0 to 10.0; EPSS first scored at 57.8%
2026-07-24 EPSS 57.8% to 88.2%

Recorded by Senserva on the dates shown, from CISA KEV and FIRST EPSS. This is what moved and when, which neither the vendor advisory nor NVD publishes.

CISA required action

Federal (BOD 22-01) remediation due date: 2026-02-27 (past due).

Please adhere to CISA’s guidelines to assess exposure and mitigate risks associated with Cisco SD-WAN devices as outlines in CISA’s Emergency Directive 26-03 (URL listed below in Notes) and CISA’s “Hunt & Hardening Guidance for Cisco SD-WAN Devices (URL listed below in Notes). Adhere to the applicable BOD 22-01 guidance for cloud services or discontinue use of the product if mitigations are not available.

Official fix for CVE-2026-20127

The authoritative fix and affected-version list are published by the vendor. Find the Catalyst SD-WAN Controller and Manager advisory on Cisco Security Advisories (PSIRT).

Cisco Security Advisories (PSIRT)CISA KEV entry

Common questions about CVE-2026-20127

Is CVE-2026-20127 actively exploited?

Yes. CVE-2026-20127 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2026-02-25, which means exploitation in the wild has been confirmed, not predicted. Its EPSS 30-day exploitation probability is 88%.

What is the CISA deadline and required action for CVE-2026-20127?

CISA set the federal (BOD 22-01) remediation due date at 2026-02-27, which has passed; treat any unremediated system as overdue. The verbatim required action: Please adhere to CISA’s guidelines to assess exposure and mitigate risks associated with Cisco SD-WAN devices as outlines in CISA’s Emergency Directive 26-03 (URL listed below in Notes) and CISA’s “Hunt & Hardening Guidance for Cisco SD-WAN Devices (URL listed below in Notes). Adhere to the applicable BOD 22-01 guidance for cloud services or discontinue use of the product if mitigations are not available.

What fixes CVE-2026-20127?

The authoritative fix is in the vendor advisory: see Cisco Security Advisories (PSIRT) for the patched Catalyst SD-WAN Controller and Manager versions and any workarounds. KEV listing makes this a fix-first item: patch it ahead of higher-CVSS issues nobody is exploiting.

Can I ask my own AI about CVE-2026-20127?

Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2026-20127's key facts: severity, CVSS, EPSS, the KEV date, the CISA due date, and the required action. Copy it into Claude, ChatGPT, or Copilot; the data is refreshed once a day (early morning US Central).

Scope and sources

More exploited Cisco CVEs: CVE-2026-20349 CVE-2026-20316 CVE-2008-4128 CVE-2026-20230 CVE-2026-20262 CVE-2026-20245 CVE-2026-20182 CVE-2026-20133
All Cisco exploited CVEs on one page: Cisco vulnerabilities actively exploited.
Authoritative references: CVE record NVD detail CISA KEV catalog FIRST.org EPSS

Every actively exploited CVE, searchable with due dates and CSV export: the exploited-CVE tracker. The newest additions: exploited this week.