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Fencer Intel
medium 4.7

CVE-2009-5023 json

The (1) dshield.conf, (2) mail-buffered.conf, (3) mynetwatchman.conf, and (4) mynetwatchman.conf actions in action.d/ in Fail2ban before 0.…

published 12y ago modified 4mo ago also EUVD-2009-4981

cvss
4.7
version 2.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 27%
public exploits
0
none known

Summary

The (1) dshield.conf, (2) mail-buffered.conf, (3) mynetwatchman.conf, and (4) mynetwatchman.conf actions in action.d/ in Fail2ban before 0.8.5 allows local users to write to arbitrary files via a symlink attack on temporary files with predictable names, as demonstrated by /tmp/fail2ban-mail.txt.

Patch / fix

  • fail2ban Debian 14, Debian 13, Debian 12 0.8.4+svn20110323-1

debian advisories DEBIAN-CVE-2009-5023

  • fail2ban openSUSE Tumbleweed 0.9.5-1.1

opensuse advisories openSUSE-SU-2024:10347-1

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2009-5023 updated cvss 3.3

fail2ban: Use of insecure default temporary file when unbanning an IP

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.34% chance of exploitation in the next 30 days, higher than 27% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 2.0 4.7 AV:L/AC:M/Au:N/C:N/I:C/A:N

Classification

Weakness
  • CWE-59 Improper Link Resolution Before File Access

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.