Vulnerabilities
Misconfiguration
Compliance
CVE Vulnerabilities

CVE-2009-5023

Improper Link Resolution Before File Access ('Link Following')

Published: Jun 10, 2014 | Modified: Apr 12, 2025
CVSS 3.x
N/A
Source:
NVD
CVSS 2.x
4.7 MEDIUM
AV:L/AC:M/Au:N/C:N/I:C/A:N
RedHat/V2
RedHat/V3
Ubuntu
LOW
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Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2009-5023
CWEhttps://cwe.mitre.org/data/definitions/59.html

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.

Weakness

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

Affected Software

NameVendorStart VersionEnd Version
Fail2banFail2ban*0.8.4 (including)
Fail2banFail2ban0.1.0 (including)0.1.0 (including)
Fail2banFail2ban0.1.1 (including)0.1.1 (including)
Fail2banFail2ban0.1.2 (including)0.1.2 (including)
Fail2banFail2ban0.3.0 (including)0.3.0 (including)
Fail2banFail2ban0.3.1 (including)0.3.1 (including)
Fail2banFail2ban0.4.0 (including)0.4.0 (including)
Fail2banFail2ban0.4.1 (including)0.4.1 (including)
Fail2banFail2ban0.5.0 (including)0.5.0 (including)
Fail2banFail2ban0.5.1 (including)0.5.1 (including)
Fail2banFail2ban0.5.2 (including)0.5.2 (including)
Fail2banFail2ban0.5.3 (including)0.5.3 (including)
Fail2banFail2ban0.5.4 (including)0.5.4 (including)
Fail2banFail2ban0.5.5 (including)0.5.5 (including)
Fail2banFail2ban0.6.0 (including)0.6.0 (including)
Fail2banFail2ban0.6.1 (including)0.6.1 (including)
Fail2banFail2ban0.7.0 (including)0.7.0 (including)
Fail2banFail2ban0.7.1 (including)0.7.1 (including)
Fail2banFail2ban0.7.2 (including)0.7.2 (including)
Fail2banFail2ban0.7.3 (including)0.7.3 (including)
Fail2banFail2ban0.7.4 (including)0.7.4 (including)
Fail2banFail2ban0.7.5 (including)0.7.5 (including)
Fail2banFail2ban0.7.6 (including)0.7.6 (including)
Fail2banFail2ban0.7.7 (including)0.7.7 (including)
Fail2banFail2ban0.7.8 (including)0.7.8 (including)
Fail2banFail2ban0.7.9 (including)0.7.9 (including)
Fail2banFail2ban0.8.0 (including)0.8.0 (including)
Fail2banFail2ban0.8.1 (including)0.8.1 (including)
Fail2banFail2ban0.8.2 (including)0.8.2 (including)
Fail2banFail2ban0.8.3 (including)0.8.3 (including)
Fail2banUbuntuhardy*
Fail2banUbuntulucid*
Fail2banUbuntumaverick*
Fail2banUbuntunatty*
Fail2banUbuntuupstream*

Potential Mitigations

  • Follow the principle of least privilege when assigning access rights to entities in a software system.
  • Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.

References

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