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Full vulnerability report · 2025
CVE-2025-20393High confidence

Cisco Multiple Products Improper Input Validation Vulnerability

Cisco · Multiple Products

Official source article: Cisco CISCO-SA-SMA-ATTACK-N9BF4 ↗. Check the applicable product and release in the original source.

10.0CriticalCVSS 3.1
Recommended action
Mitigate now

CISA confirms exploitation in the wild and lists 2025-12-24 as the remediation due date.

Mitigation available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityCriticalOperational priority:Critical, unchanged from published severity.unchanged

Evidence used

  • CISA confirms exploitation in the wild.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 32.39% for the current model date.

Compensating controls

  • Apply the linked authoritative mitigation while planning the permanent fix.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs Cisco Multiple Products and falls inside the recorded affected range.
  2. Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 3 daysRemediation target: Within 90 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2025-203911

CISA KEV mirrored by ENISA

A vulnerability in the Spam Quarantine feature of Cisco AsyncOS Software for Cisco Secure Email Gateway and Cisco Secure Email and Web Manager could allow an unauthenticated, remote attacker to execute arbitrary system commands on an affected device with root privileges. This vulnerability is due to insufficient validation of HTTP requests by the Spam Quarantine feature. An attacker could exploit this vulnerability by sending a crafted HTTP request to the affected device. A successful exploit could allow the attacker to execute arbitrary commands on the underlying operating system with root privileges.

EUVD state
Present in the current official mapping
Known exploitation
Recorded by ENISA since 17 Dec 2025. Evidence sources: cisa_kev.
ENISA score
10.0 · CVSS 3.1
Advisory evidence
3 linked advisory records
Recommended actionMitigate now

CISA confirms exploitation in the wild and lists 2025-12-24 as the remediation due date.

Mitigation available
01

What, why and how

Cisco Secure Email Gateway, Secure Email, AsyncOS Software, and Web Manager appliances contains an improper input validation vulnerability that allows threat actors to execute arbitrary commands with root privileges on the underlying operating system of an affected appliance.

What

Cisco Secure Email Gateway, Secure Email, AsyncOS Software, and Web Manager appliances contains an improper input validation vulnerability that allows threat actors to execute arbitrary commands with root privileges on the underlying operating system of an affected appliance.

Why

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.

What

Cisco Secure Email Gateway, Secure Email, AsyncOS Software, and Web Manager appliances contains an improper input validation vulnerability that allows threat actors to execute arbitrary commands with root privileges on the underlying operating system of an affected appliance.

Why

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Confirmed in the wild

CISA added this CVE to its Known Exploited Vulnerabilities catalogue on 2025-12-17.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Improper Input Validation → execute code or commands in the affected security context
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Changed: exploitation can affect a different security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-20 ↗

CWE-20: Improper Input Validation. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SChangedScope: The attack can affect a component governed by a different security authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
After compromise, an attacker may use built-in shells, scripting engines, scheduled tasks and native network utilities for discovery, persistence or movement. This is a plausible LoTL path, not evidence that it has occurred for every attack.
NetworkUnauthenticatedRemote code executionCWE-20CISA KEV
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2025-203911Known-exploited evidence recorded

A vulnerability in the Spam Quarantine feature of Cisco AsyncOS Software for Cisco Secure Email Gateway and Cisco Secure Email and Web Manager could allow an unauthenticated, remote attacker to execute arbitrary system commands on an affected device with root privileges. This vulnerability is due to insufficient validation of HTTP requests by the Spam Quarantine feature. An attacker could exploit this vulnerability by sending a crafted HTTP request to the affected device. A successful exploit could allow the attacker to execute arbitrary commands on the underlying operating system with root privileges.

Official EUVD record ↗
BSI · German · WID-SEC-2025-2870Cisco AsyncOS für Secure Email Gateway: Schwachstelle ermöglicht Ausführen von beliebigem Programmcode mit Administratorrechten

Ein entfernter, anonymer Angreifer kann eine Schwachstelle in Cisco AsyncOS und Cisco Secure Email Gateway ausnutzen, um beliebigen Programmcode mit Administratorrechten auszuführen.

Official advisory ↗
Canadian Centre for Cyber Security · English · AV25-848Cisco security advisory (AV25-848) – Update 1

On December 17, 2025, Cisco published a security advisory to address a critical vulnerability in the following products: Update 1

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20251224Security Bulletin 24 Dec 2025

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 24 Dec 2025, published on 24 December 2025. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2025-AVI-1120Vulnérabilité dans les produits Cisco

Une vulnérabilité a été découverte dans les produits Cisco. Elle permet à un attaquant de provoquer une exécution de code arbitraire à distance avec les droits administrateurs. Cisco indique que cette vulnérabilité est activement exploitée et fournit des recommandations dans son bulletin de sécurité.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2025-022547シスコシステムズの Cisco AsyncOS における入力確認に関する脆弱性

シスコシステムズの Cisco AsyncOS には、入力確認に関する脆弱性が存在します。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-6648美 CISA 발표 주요 Exploit 정보공유(Update. 2025-12-17)

Cisco Secure Email Gateway, Secure Email, AsyncOS Software, and Web Manager appliances contains an improper input validation vulnerability that allows threat actors to execute arbitrary commands with root privileges on the underlying operating system of an affected appliance.

Official advisory ↗
NCSC-NL · Dutch · NCSC-2025-0398Kwetsbaarheid in Cisco AsyncOS

Cisco is investigating a cyberattack campaign targeting appliances running Cisco AsyncOS Software, which may be vulnerable due to open ports.

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Mitigation available
Affected
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
The Cyber Centre encourages users and administrators to review the provided web links, perform the suggested recommendations and apply the necessary updates when available.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 17 Dec 2025 · Last source change 26 Feb 2026, 16:07 UTC · CWE-20 · Improper Input Validation

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2025-203911
Product sourceCISA KEV
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Vendor guidanceAuthoritative vendor guidance changed: removed remediation: cyber.gc.ca/cisco-security-advisory-av25-848.
    Before
    remediation: cyber.gc.ca/cisco-security-advisory-av25-848 · vendor advisory: sec.cloudapps.cisco.com/cisco-sa-sma-attack-N9bf4
    After
    vendor advisory: sec.cloudapps.cisco.com/cisco-sa-sma-attack-N9bf4
    psirt@cisco.com ↗
  2. Remediation statusRemediation status changed from Mitigation available to Awaiting fix.
    Before
    Mitigation available
    After
    Awaiting fix
    psirt@cisco.com ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    14.0.0-698; 13.5.1-277; 13.0.0-392; 14.2.0-620; 13.0.5-007; 13.5.4-038; 14.2.1-020; 14.3.0-032 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    Cisco Secure Email: 14.0.0-698, 13.5.1-277, 13.0.0-392, 14.2.0-620, 13.0.5-007, 13.5.4-038, 14.2.1-020, 14.3.0-032, 15.0.0-104, 15.0.1-030, 15.5.0-048, 15.5.1-055, 15.5.2-018, 16.0.0-050, 15.0.3-002, 16.0.0-054, 15.5.3-022, 16.0.1-017; Cisco Secure Email and Web Manager: 13.6.2-023, 13.6.2-078, 13.0.0-249, 13.0.0-277, 13.8.1-052, 13.8.1-068, 13.8.1-074, 14.0.0-404, 12.8.1-002, 14.1.0-227, 13.6.1-201, 14.2.0-203, 14.2.0-212, 12.8.1-021, 13.8.1-108, 14.2.0-224, 14.3.0-120, 15.0.0-334, 15.5.1-024, 15.5.1-029, 15.5.2-005, 16.0.0-195, 15.5.3-017, 16.0.1-010, 15.0.1-035, 16.0.2-088 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
  4. Remediation statusRemediation status changed from Awaiting fix to Mitigation available.
    Before
    Awaiting fix
    After
    Mitigation available
    Canadian Centre for Cyber Security ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Added to CISA KEV
Remediation guidance recorded
ENISA EUVD · EUVD-2025-203911↗Canadian Centre for Cyber Security remediation guidance↗CISA KEV record↗CVE authority or vendor reference · Cisco CISCO-SA-SMA-ATTACK-N9BF4↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2025-20393 · cve.blacktree.nl