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Cisco Email Gateway Zero Day Let Attackers Gain Root Access Remotely

Part of the CVE-2026-76461 story · since 14 Sep

Quiet for 2 weekslast report 15 Oct10 articles7 outlets
14 Sep · CISA first1 Oct9 Oct17 OctNowThis article5th of 10
  • Mon 14 Sep, 20:32 UTC. CISA, first report. CISA Warns of Actively Exploited Cisco Email Gateway Flaw. Cites a CVE in CISA KEV.
  • Tue 15 Sep, 04:41 UTC. SecurityOnline, its first report on the story. Cisco Email Gateway Flaw Exploited to Gain Root Access via Email. Cites a CVE in CISA KEV.
  • Tue 15 Sep, 05:52 UTC. SecurityWeek, its first report on the story. Cisco Secure Email Gateways Hit by Actively Exploited Root Flaw. Cites a CVE in CISA KEV.
  • Tue 15 Sep, 13:13 UTC. Security Affairs, its first report on the story. Cisco Secure Email Gateways Hit by Actively Exploited Root Access Zero Day. Cites a CVE in CISA KEV.
  • Tue 15 Sep, 13:13 UTC. Rapid7, its first report on the story. Cisco Email Gateway Zero Day Let Attackers Gain Root Access Remotely. Cites a CVE in CISA KEV. This article, 5th of 10.
  • Tue 15 Sep, 21:21 UTC. Security Affairs. CISA Flags Critical Cisco Email Gateway Flaw Exploited in Attacks. Cites a CVE in CISA KEV.
  • Wed 16 Sep, 14:51 UTC. SOCRadar, its first report on the story. Cisco Warns Attackers Are Exploiting Critical Secure Email Gateway Flaw. Cites a CVE in CISA KEV.
  • Mon 21 Sep, 02:59 UTC. SecurityOnline. Cisco Warns of Actively Exploited Flaws Enabling Root Access. Cites a CVE in CISA KEV.
  • Wed 14 Oct, 19:26 UTC. The Hacker News, its first report on the story. Cisco Email Gateway Flaw Exploited to Run Commands as Root. Cites a CVE in CISA KEV.
  • Thu 15 Oct, 07:01 UTC. SecurityWeek. Attackers Exploit Critical Cisco Email Gateway Flaw to Gain Root Access. Cites a CVE in CISA KEV.

Rapid7 says Cisco Secure Email Gateway is affected by CVE-2026-76461, a critical SQL injection vulnerability in AsyncOS Software. Cisco published its advisory on 14 September 2026, reporting a CVSS v3.1 score of 9.8. The flaw could allow an unauthenticated, remote attacker to execute arbitrary commands with root privileges by sending a specially crafted email through a vulnerable appliance; access to the administrative interface is not required.

Cisco’s PSIRT became aware of active exploitation in September, and the vulnerability was added to the US Cybersecurity and Infrastructure Security Agency’s Known Exploited Vulnerabilities catalogue on the same day, indicating zero-day exploitation before disclosure. No public proof-of-concept code or threat-actor attribution was available when Rapid7 published its report.

Organisations should urgently install Cisco’s fixed releases rather than wait for their normal patching cycle. Version 15.5 and earlier is fixed in 15.5.5-014, version 16.0 in 16.0.4-302, and version 16.5 in 16.5.0-780. Cisco strongly recommends migrating to 16.5.0-780. Administrators can investigate possible exploitation by reviewing the `mail_logs` on every appliance, including each device in a cluster, for suspicious SQL statements. Cisco’s advisory gives `COPY ... TO PROGRAM` as an example; its presence may indicate malicious activity.

How the story developed

All 10 articles
Quiet for 2 weekslast report 15 Oct10 articles7 outlets

10 articles from 7 outlets since 14 Sep. Quiet since 15 Oct. This was the 5th report, 17 hours after the first.

Now14 Sep171819202115 OctFirst reportCISA · 14 Sep, 20:32This article5th of 10 · day 1
  • Mon 14 Sep, 20:32 UTC. CISA, first report. CISA Warns of Actively Exploited Cisco Email Gateway Flaw. Cites a CVE in CISA KEV.
  • Tue 15 Sep, 04:41 UTC. SecurityOnline, its first report on the story. Cisco Email Gateway Flaw Exploited to Gain Root Access via Email. Cites a CVE in CISA KEV.
  • Tue 15 Sep, 05:52 UTC. SecurityWeek, its first report on the story. Cisco Secure Email Gateways Hit by Actively Exploited Root Flaw. Cites a CVE in CISA KEV.
  • Tue 15 Sep, 13:13 UTC. Security Affairs, its first report on the story. Cisco Secure Email Gateways Hit by Actively Exploited Root Access Zero Day. Cites a CVE in CISA KEV.
  • Tue 15 Sep, 13:13 UTC. Rapid7, its first report on the story. Cisco Email Gateway Zero Day Let Attackers Gain Root Access Remotely. Cites a CVE in CISA KEV. This article, 5th of 10.
  • Tue 15 Sep, 21:21 UTC. Security Affairs. CISA Flags Critical Cisco Email Gateway Flaw Exploited in Attacks. Cites a CVE in CISA KEV.
  • Wed 16 Sep, 14:51 UTC. SOCRadar, its first report on the story. Cisco Warns Attackers Are Exploiting Critical Secure Email Gateway Flaw. Cites a CVE in CISA KEV.
  • Mon 21 Sep, 02:59 UTC. SecurityOnline. Cisco Warns of Actively Exploited Flaws Enabling Root Access. Cites a CVE in CISA KEV.
  • Wed 14 Oct, 19:26 UTC. The Hacker News, its first report on the story. Cisco Email Gateway Flaw Exploited to Run Commands as Root. Cites a CVE in CISA KEV.
  • Thu 15 Oct, 07:01 UTC. SecurityWeek. Attackers Exploit Critical Cisco Email Gateway Flaw to Gain Root Access. Cites a CVE in CISA KEV.
  • Known exploited CVE
  • No CVE
  • Larger: an outlet’s first report
  • Square: official source
  • Coverage over time
  • Quiet time, folded
Show all 10 articles as a list
  1. Mon 14 SepDay 01
    1. CISA Warns of Actively Exploited Cisco Email Gateway Flaw20:32 · CISA · official · First report · CISA alert · Known exploited CVE
  2. Tue 15 SepDay 15
    1. Cisco Email Gateway Flaw Exploited to Gain Root Access via Email04:41 · SecurityOnline · Known exploited CVE
    2. Cisco Secure Email Gateways Hit by Actively Exploited Root Flaw05:52 · SecurityWeek · Known exploited CVE
    3. Cisco Email Gateway Zero Day Let Attackers Gain Root Access Remotely13:13 · Rapid7 · Known exploited CVE · This article, 5th of 10
    Show 2 more from 15 Sep
    1. Cisco Secure Email Gateways Hit by Actively Exploited Root Access Zero Day13:13 · Security Affairs · Known exploited CVE
    2. CISA Flags Critical Cisco Email Gateway Flaw Exploited in Attacks21:21 · Security Affairs · Known exploited CVE
  3. Wed 16 SepDay 21
    1. Cisco Warns Attackers Are Exploiting Critical Secure Email Gateway Flaw14:51 · SOCRadar · Known exploited CVE

  4. Quiet for 5 days

    Mon 21 SepDay 71
    1. Cisco Warns of Actively Exploited Flaws Enabling Root Access02:59 · SecurityOnline · Picked up again · Known exploited CVE

  5. Quiet for 3 weeks

    Wed 14 OctDay 301
    1. Cisco Email Gateway Flaw Exploited to Run Commands as Root19:26 · The Hacker News · Picked up again · Known exploited CVE
  6. Thu 15 OctDay 311
    1. Attackers Exploit Critical Cisco Email Gateway Flaw to Gain Root Access07:01 · SecurityWeek · Known exploited CVE

Sources

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