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CVE-2007-4321· NVD / CVE Program· CNA mitre

fail2ban 0.8 and earlier does not properly parse sshd log files, which allows remote attackers to add arbitrary hosts to the /etc/hosts.deny

fail2ban 0.8 and earlier does not properly parse sshd log files, which allows remote attackers to add arbitrary hosts to the /etc/hosts.deny file and cause a denial of service by adding arbitrary IP addresses to the sshd log file, as demonstrated by logging in via ssh with a client protocol version identification containing an IP address string, a different vector than CVE-2006-6302.

MediumCVSS 6.8 · v2.0—Proof of concept Fix available
Published
Aug 13, 2007
Updated
Jun 16, 2026
EPSS
5.7% · 93th percentile
CWE
—
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Report tools

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Action score

29

Monitor

Low priority for now.

CVSS
27 / 40 · 6.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
2 / 30 · 5.7%

Noroxi analysis

No Noroxi analysis for this record yet

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Affected systems

VendorProduct
fail2banfail2ban

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • fail2ban fail2ban0.8

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12fail2banbefore 0.8.0-40.8.0-4
Debian:4.0fail2banbefore 0.7.5-2etch10.7.5-2etch1

Same product

fail2ban: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-32749Possible RCE vulnerability in mailing action using mailutils (mail-whois)
    33Monitor
  • CVE-2012-5642server/action.py in Fail2ban before 0.8.8 does not properly handle the content of the matches tag, which might allow remote attackers to tri
    31Monitor
  • CVE-2013-7177config/filter.d/cyrus-imap.conf in the cyrus-imap filter in Fail2ban before 0.8.11 allows remote attackers to trigger the blocking of an arb
    21Monitor
  • CVE-2013-7176config/filter.d/postfix.conf in the postfix filter in Fail2ban before 0.8.11 allows remote attackers to trigger the blocking of an arbitrary
    21Monitor
  • CVE-2013-2178The apache-auth.conf, apache-nohome.conf, apache-noscript.conf, and apache-overflows.conf files in Fail2ban before 0.8.10 do not properly va
    21Monitor
  • CVE-2006-6302fail2ban 0.7.4 and earlier does not properly parse sshd log files, which allows remote attackers to add arbitrary hosts to the /etc/hosts.de
    21Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:fail2ban0.8.0-4 · Debian:12Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Exploit-DB entry ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Exploit-DB entrydos2007-07-28

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. First PoC-17 d
  2. Published
  3. TodayOct 11, 2026+6998 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

    If successful

    Confidentiality
    P · data can be read
    Integrity
    P · data or configuration can be modified
    Availability
    P · the service can be disrupted
    Attack complexity
    M
    Confidentiality impact
    P
    Integrity impact
    P
    Availability impact
    P

    Weakness class (CWE)

    —

    CVSS vector

    AV:N/AC:M/Au:N/C:P/I:P/A:P

    nvd-primary

    Attack context

    MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

    MITRE has no CAPEC/ATT&CK mapping for this CWE.

    Change log

    1. Fix✗ → ✓

    For records you follow, these changes also arrive as notifications. →

    References

    Vendor advisories and official records. Exploit/PoC links are deliberately left out.

    All records