CVE-2018-13796 — mailman
MEDIUMCVE-2018-13796 is a medium-severity (CVSS 6.5) Improper Input Validation vulnerability in mailman. A fix is available for mailman — see the affected versions and patch details below.
Moderate severity vulnerability that affects mailman
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2018-13796 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
mailmanReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | mailman | all versions | 2.1.28pip install --upgrade 'mailman==2.1.28' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mailman, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update mailman to 2.1.28 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-13796 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2018-13796 can be triaged on real exposure rather than presence alone.
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.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 7 | mailman-3:2.1.15-30.el7 | RHSA-2020:1054 |
Frequently Asked Questions
Is CVE-2018-13796 in your dependencies?
O3 Security finds CVE-2018-13796 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.