CriticalCVE-2026-76461

    Cisco Secure Email Gateway SQL Injection Vulnerability (CVE-2026-76461)

    Published Last modified In CISA KEV since Sources: Cisco PSIRT, CVE.org, BSI

    What is affected, what to do

    A vulnerability in the email parsing of Cisco AsyncOS Software for Cisco Secure Email Gateway could allow an unauthenticated, remote attacker to execute arbitrary commands with root privileges on the underlying operating system. This vulnerability is due to insufficient validation in the email parsing logic.

    The vulnerability is being actively exploited; treat it as a priority. Update Secure Email Gateway AsyncOS to version 15.5.5-014. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Cisco Secure Email eq 14.0.0-698..14.0.0-698
    • Cisco Secure Email eq 13.5.1-277..13.5.1-277
    • Cisco Secure Email eq 13.0.0-392..13.0.0-392
    • Cisco Secure Email eq 14.2.0-620..14.2.0-620
    • Cisco Secure Email eq 13.0.5-007..13.0.5-007
    • Cisco Secure Email eq 13.5.4-038..13.5.4-038
    • Cisco Secure Email eq 14.2.1-020..14.2.1-020
    • Cisco Secure Email eq 14.3.0-032..14.3.0-032
    • Cisco Secure Email eq 15.0.0-104..15.0.0-104
    • Cisco Secure Email eq 15.0.1-030..15.0.1-030
    • Cisco Secure Email eq 15.5.0-048..15.5.0-048
    • Cisco Secure Email eq 15.5.1-055..15.5.1-055
    • Cisco Secure Email eq 15.5.2-018..15.5.2-018
    • Cisco Secure Email eq 16.0.0-050..16.0.0-050
    • Cisco Secure Email eq 15.0.3-002..15.0.3-002
    • Cisco Secure Email eq 16.0.0-054..16.0.0-054
    • Cisco Secure Email eq 15.5.3-022..15.5.3-022
    • Cisco Secure Email eq 16.0.1-017..16.0.1-017
    • Cisco Secure Email eq 15.5.4-012..15.5.4-012
    • Cisco Secure Email eq 16.0.4-016..16.0.4-016
    • Cisco Secure Email eq 15.0.5-016..15.0.5-016
    • Cisco Secure Email eq 16.0.2-112..16.0.2-112
    • Cisco Secure Email eq 16.0.3-044..16.0.3-044

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    9.8

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    9.8

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: Cisco PSIRT, CVE.org, BSI

    29.5 %

    EPSS score

    Elevated — model estimates 10-50% exploitation likelihood.

    Source: FIRST EPSS, percentile 98.2

    Show all metrics
    Severity
    Critical
    Priority score

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    255.07
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    actively exploited (KEV)Source: VulnCheck KEV (opens in a new tab)
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    9.8
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    9.8
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    29.5 %
    Elevated — model estimates 10-50% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    98.2
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    Actively exploited
    Published
    In CISA KEV since

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-89

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This flaw is reachable over the network with no authentication and no user interaction, and lands directly in root-level command execution — on an appliance that by design accepts mail from the entire internet and therefore cannot simply be firewalled off. Email gateways are prized initial-access targets: they see all mail traffic, hold directory credentials and sit outside typical EDR coverage, and this CVE ranks among those most likely to be exploited. CISA has not flagged ransomware use, but the appliance is an ideal foothold for espionage, mail tampering and lateral movement. Treat any internet-facing gateway on an affected build as P1 requiring patching plus forensic review within 24 hours; internal-only instances with no external mail intake can follow, but within days, not weeks.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Inventory and version check: Enumerate every Cisco Secure Email Gateway (hardware, virtual, cloud-hosted) and confirm via the CLI version command or the GUI whether it runs an affected AsyncOS build: 13.0.0-392, 13.0.5-007, 13.5.1-277, 13.5.4-038, 14.0.0-698, 14.2.0-620, 14.2.1-020, 14.3.0-032.
      • Patch: Patch available from the vendor — look up the fixed AsyncOS release in the Cisco Security Advisory. Push it as an emergency change outside the normal maintenance window; in clusters, upgrade nodes one at a time to keep mail flowing.
      • Compromise assessment before patching: Exploitation needs only one crafted inbound email, no credentials, and yields root, so treat every internet-facing affected gateway as potentially compromised. Export mail_logs, authentication, cli_logs, gui_logs and configuration history to the SIEM before upgrading; if anything looks off, engage Cisco TAC and prefer a rebuild over an in-place upgrade.
      • Rotate secrets: Assume every secret on the appliance is exposed — local admin accounts, LDAP/AD bind account, SMTP AUTH credentials, API tokens, SNMP communities, TLS certificates and private keys (including DKIM signing keys). Reissue or rotate.
      • Lock down management: Restrict the HTTPS GUI, SSH/22 and the API to a dedicated management network or jump hosts; disable management on the public-facing interface.
      • Regulatory clock: NIS2/KRITIS entities should prepare the 24-hour early warning to the national authority (BSI in Germany) if compromise indicators surface.

    2. Runbook step 2

      Mitigation layers

      • Upstream filtering (network): If patching must wait, temporarily repoint MX records to an alternative, unaffected filtering service (e.g. a third-party cloud mail filter) and firewall inbound TCP/25 on the gateway to that provider's ranges only. This removes direct internet reachability of the vulnerable parser.
      • Egress control (segmentation): Allowlist outbound traffic from the gateway — DNS resolvers, internal mail servers, Cisco update and Talos endpoints, NTP, syslog. Block and log everything else (arbitrary TCP, outbound SSH, HTTP to unknown hosts) to frustrate reverse shells and exfiltration.
      • IPS signature (SMTP content): On the upstream IPS (Suricata/Snort, Firepower) add a temporary rule for SMTP on TCP/25 matching SQL metacharacters in headers and MIME fields, e.g. content:"UNION"; nocase; pcre:"/(UNION\s+SELECT|;\s*--|'\s*OR\s*'1'='1|SLEEP\s*\()/i". Run in alert mode first to gauge false positives on legitimate mail.
      • IAM / least privilege: Scope the gateway's LDAP bind account to read-only; never store domain-privileged accounts on the appliance. Enforce MFA or SAML for administration.
      • Log integrity: Forward all AsyncOS log types to an external, write-once syslog target — a root-level attacker can tamper with local logs.
      • Segmentation: Host the gateway in its own DMZ; permit inbound-to-internal traffic only to required mail servers on TCP/25 or TCP/587 and to LDAP.

    3. Runbook step 3

      Detection rules

      • AsyncOS mail_logs / Message Tracking: Hunt for SQL fragments in subject, sender, recipient, Message-ID or attachment names. SPL: index=email sourcetype=cisco:esa* | regex _raw="(?i)(union\s+select|;\s*--|sleep\s*\(|pg_sleep|xp_cmdshell|'\s*or\s*'1'='1)".
      • Network telemetry (Zeek conn.log, firewall logs): Outbound connections sourced from the gateway to non-allowlisted destinations, especially odd ports or long-lived sessions. KQL shape: CommonSecurityLog | where SourceIP in (seg_ips) and DestinationIP !in (allowlist) | summarize count() by DestinationIP, DestinationPort.
      • Zeek smtp.log / Suricata: Inbound SMTP transactions with SQL metacharacters in subject, mailfrom, rcptto or header fields; Sigma shape: logsource: product: zeek, service: smtp with selection: subject|re: '(?i)(union.+select|;--)'.
      • AsyncOS authentication / cli_logs / config history: New local users, unexpected changes to content or message filters, forwarding or BCC actions, enabling of remote-access features, or off-hours admin logins.
      • DNS telemetry: Gateway lookups of newly registered or rare domains, or unusually long subdomains suggesting DNS tunnelling.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    A vulnerability in the email parsing of Cisco AsyncOS Software for Cisco Secure Email Gateway could allow an unauthenticated, remote attacker to execute arbitrary commands with root privileges on the underlying operating system. This vulnerability is due to insufficient validation in the email parsing logic. An attacker could exploit this vulnerability by sending a crafted email message that contains malicious SQL statements through an affected device. A successful exploit could allow the attacker to execute arbitrary SQL statements, leading to command execution with root privileges on the underlying operating system.

    Source: cisco_csaf, NVD (NIST), CISA KEV Catalog, CVE.org (MITRE), cvelistv5, BSI CSAF, BSI WID Portal

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    VendorProductAffected versionsFixed in
    CiscoCisco Secure Email
    • 13.0.0-392
    • 13.0.5-007
    • 13.5.1-277
    • 13.5.4-038
    • 14.0.0-698
    • 14.2.0-620
    • 14.2.1-020
    • 14.3.0-032
    • 15.0.0-104
    • 15.0.1-030
    • 15.0.3-002
    • 15.0.5-016
    • 15.5.0-048
    • 15.5.1-055
    • 15.5.2-018
    • 15.5.3-022
    • 15.5.4-012
    • 16.0.0-050
    • 16.0.0-054
    • 16.0.1-017
    • 16.0.2-112
    • 16.0.3-044
    • 16.0.4-016
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    CiscoSecure Email Gateway AsyncOS
    • < 15.5.5-014
    • < 16.0.4-302
    • < 16.5.0-780
    • 15.5.5-014
    • 16.0.4-302
    • 16.5.0-780

    Affected operating systems

    Affected operating systems
    FamilyVendorProductVersion
    Otherciscoasyncos—

    Weakness classes (CWE)

    • CWE-89Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')

      Base

      The product constructs all or part of an SQL command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended SQL command when it is sent to a downstream component. Without sufficient removal or quoting of SQL syntax in user-controllable inputs, the generated SQL query can cause those inputs to be interpreted as SQL instead of ordinary user data.

      Entry at MITRE CWE-89

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    SourceReferenceMaturityPublished
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited (KEV)
    PoC-in-GitHub (nomi-sec)CVE-2026-76461 (opens in a new tab)github.comPoC (publicly reported)reported, not verified
    PoC-in-GitHub (nomi-sec)CVE-2026-76461 (opens in a new tab)github.comPoC (publicly reported)reported, not verified
    PoC-in-GitHub (nomi-sec)CVE-2026-76461 (opens in a new tab)github.comPoC (publicly reported)reported, not verified

    References & sources

    Reanalysis & status changes

    Chronological NVD audit events for this CVE — reanalyses, CVSS updates, CPE diffs.

    1. Initial Analysisnvd@nist.gov

      • CPE Configuration: after AND OR *cpe:2.3:o:cisco:asyncos:*:*:*:*:*:*:*:* versions up to (excluding) 15.5.5-014 *cpe:2.3:o:cisco:asyncos:*:*:*:*:*:*:*:* versions from (including) 16.0 up to (excluding) 16.0.4-302 *cpe:2.3:o:cisco:asyncos:*:*:*:*:*:*:*:* versions from (including) 16.5 up to (excluding) 16.5.0-780 OR cpe:2.3:a:cisco:secure_email_gateway_virtual_appliance_c100v:-:*:*:*:*:*:*:* cpe:2.3:a:cisco:secure_email_gateway_virtual_appliance_c300v:-:*:*:*:*:*:*:* cpe:2.3:a:cisco:secure_email_gateway_virtual_appliance_c600v:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:secure_email_gateway_c195:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:secure_email_gateway_c395:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:secure_email_gateway_c695:-:*:*:*:*:*:*:*
      • Reference Type: after Cisco Systems, Inc.: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-esa-inj-2bLVGmhX Types: Vendor Advisory
      • Reference Type: after CISA-ADP: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-76461 Types: US Government Resource

    2. CVE Modified134c704f-9b21-4f2e-91b3-4a467353bcc0

      • SSVC: before {"id":"CVE-2026-76461","role":"CISA Coordinator","options":[{"exploitation":"active"},{"automatable":"yes"},{"technic… after {"id":"CVE-2026-76461","role":"CISA Coordinator","options":[{"exploitation":"active"},{"automatable":"yes"},{"technic…

    3. CVE CISA KEV Update9119a7d8-5eab-497f-8521-727c672e3725

      • Date Added: after 2026-09-14
      • Due Date: after 2026-09-14
      • Required Action: after 2026-09-14
      • Vulnerability Name: after 2026-09-14

    4. CVE Modified134c704f-9b21-4f2e-91b3-4a467353bcc0

      • Reference: after https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-76461
      • SSVC: before {"id":"CVE-2026-76461","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"yes"},{"technical… after {"id":"CVE-2026-76461","role":"CISA Coordinator","options":[{"exploitation":"active"},{"automatable":"yes"},{"technic…

    5. New CVE Receivedpsirt@cisco.com

      • Description: after A vulnerability in the email parsing of Cisco AsyncOS Software for Cisco Secure Email Gateway could allow an unauthenticated, remote attacker to execute arbitrary commands with root privileges on the underlying operating system. This vulnerability is due to insufficient validation in the email parsing logic. An attacker could exploit this vulnerability by sending a crafted email message that contains malicious SQL statements through an affected device. A successful exploit could allow the attacker to execute arbitrary SQL statements, leading to command execution with root privileges on the underlying operating system.
      • CVSS V3.1: after AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
      • CWE: after CWE-89
      • Affected: after New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/76xxx/CVE-2026-76461.json">CVE-2026-76461</a>

    Linked advisories