How severe is CVE-2009-3421?

CVE-2009-3421 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2009-3421 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2009-3421?

CVE-2009-3421 affects Zenas Pao-bacheca Guestbook. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2009-3421?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2009-3421 published?

CVE-2009-3421 was published on 2009-09-25 and last updated on 2026-06-16.

CVE-2009-3421

CVE-2009-3421 is a critical-severity vulnerability in Zenas Pao-bacheca Guestbook with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-287.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 6.8
EPSS exploit prediction: 5% (91st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Zenas Pao-bacheca Guestbook
Published: 2009-09-25
Last modified: 2026-06-16

Description

login.php in Zenas PaoBacheca Guestbook 2.1, when register_globals is enabled, allows remote attackers to bypass authentication and gain administrative access by setting the login_ok parameter to 1.

Frequently asked questions

What is CVE-2009-3421?: login.php in Zenas PaoBacheca Guestbook 2.1, when register_globals is enabled, allows remote attackers to bypass authentication and gain administrative access by setting the login_ok parameter to 1.
How severe is CVE-2009-3421?: CVE-2009-3421 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2009-3421 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2009-3421?: CVE-2009-3421 affects Zenas Pao-bacheca Guestbook. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2009-3421?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2009-3421 published?: CVE-2009-3421 was published on 2009-09-25 and last updated on 2026-06-16.

References

Affected products (1)

cpe:2.3:a:zenas:pao-bacheca_guestbook:2.1:*:*:*:*:*:*:*

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