CVE-2009-3421

Exp

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.

Published: 2009-09-25 Last update: 2026-04-23 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2009-3421 is rated High Exploit Risk (89.5/100): CVSS Critical severity, with high exploitation likelihood (EPSS 4.99%, 91th percentile). 2 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +3.42% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2009-3421

EDB-ID Source Kind Published Link
9293 exploit_db edb 2009-07-28 Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2009-3421

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 1.57% 4.99% +3.42%
2 2026-01-15 3.03% 1.57% -1.46%
3 2025-03-30 — 3.03% —

Full EPSS history (12 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2009-3421

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
6.8 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.6 6.4 [email protected]

Weakness enumeration for CVE-2009-3421

Affected software / configurations for CVE-2009-3421

Vendor Product Version Raw CPE
zenas pao-bacheca_guestbook 2.1 cpe:2.3:a:zenas:pao-bacheca_guestbook:2.1:*:*:*:*:*:*:*

References for CVE-2009-3421

URL Tags
http://secunia.com/advisories/36023 Broken Link Vendor Advisory
http://www.exploit-db.com/exploits/9293 Third Party Advisory VDB Entry
http://www.osvdb.org/56757 Broken Link Exploit
https://exchange.xforce.ibmcloud.com/vulnerabilities/52100 Third Party Advisory VDB Entry
cvelogic Threat Intelligence