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CVE-2018-13796

MEDIUM

CVE-2018-13796 is a medium-severity (CVSS 6.5) Improper Input Validation vulnerability in gnu mailman. O3 Security detects and blocks CVE-2018-13796 exploitation at runtime via eBPF exploit-chain detection and L7 egress monitoring, even on unpatched systems.

An issue was discovered in GNU Mailman before 2.1.28. A crafted URL can cause arbitrary text to be displayed on a web page from a trusted site.

Published
Jul 12, 2018
Updated
Jun 17, 2026
Affected
1 product
Patched
See advisory
Exploits
None indexed

Description

An issue was discovered in GNU Mailman before 2.1.28. A crafted URL can cause arbitrary text to be displayed on a web page from a trusted site.

Affected Products

1 product · 1 configurations
Application
mailmangnu
< 2.1.28
range

Detection & mitigation playbook

Vendor / appliance
  1. Detect

    Inventory every gnu mailman deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.

  2. Fix

    Apply the gnu mailman security patch or hotfix for CVE-2018-13796 on the affected version, following the vendor advisory for your exact build.

  3. Workarounds

    Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.

  4. How O3 protects you

    O3 detects and blocks CVE-2018-13796 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.

Tailored to CVE-2018-13796. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

An issue was discovered in GNU Mailman before 2.1.28. A crafted URL can cause arbitrary text to be displayed on a web page from a trusted site.
O3 Security · Runtime Protection

Is CVE-2018-13796 being exploited in your environment?

O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2018-13796 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.