CVE-2012-5642: server/action.py in Fail2ban before 0.8.8 does not properly handle the content of the matches tag, which might

Q: How do I fix CVE-2012-5642?

fail2ban: upgrade to newer than 0.8.7.1. Exact commands for each OS are on this page.

Q: Is CVE-2012-5642 being exploited?

CVE-2012-5642 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2012-5642 affect?

CVE-2012-5642 affects fail2ban. Severity is high (CVSS 7.5). server/action.py in Fail2ban before 0.8.8 does not properly handle the content of the matches tag, which might allow remote attackers to trigger unsafe behavior in a custom action file via unspecified symbols in this content.

This month

HIGH 7.5UPGRADE

CVE-2012-5642 is a high-severity flaw (CVSS 7.5) affecting fail2ban. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

server/action.py in Fail2ban before 0.8.8 does not properly handle the content of the matches tag, which might allow remote attackers to trigger unsafe behavior in a custom action file via unspecified symbols in this content.

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
EPSS exploit chance	3.1% (top 12%)
CISA exploited list	No
Published	2012-12-31
Last modified	2026-06-16

Publisher (CNA): Red Hat, Inc. · Vendor: fail2ban

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2012-12-31 11:50 UTCPublished CVE record published
2026-06-16 23:47 UTCUpdated Record last modified

fail2ban fail2ban UPGRADE

Affected: <= 0.8.7.1 · 0.1.0 · 0.1.1 · 0.1.2 · 0.3.0 · 0.3.1 · 0.4.0 · 0.4.1

Fixed in: newer than 0.8.7.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy fail2ban || rpm -q fail2ban || fail2ban --version

2. UPGRADE to newer than 0.8.7.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade fail2ban

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade fail2ban

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2012-5642?

fail2ban: upgrade to newer than 0.8.7.1. Exact commands for each OS are on this page.

Is CVE-2012-5642 being exploited?

CVE-2012-5642 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2012-5642 affect?

CVE-2012-5642 affects fail2ban. Severity is high (CVSS 7.5). server/action.py in Fail2ban before 0.8.8 does not properly handle the content of the matches tag, which might allow remote attackers to trigger unsafe behavior in a custom action file via unspecified symbols in this content.

How urgent is CVE-2012-5642?

Priority 48/100. High severity

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References

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