What is CVE-2009-3294?

CVE-2009-3294 is a vulnerability in Microsoft Windows 7, classified under Use of Externally-Controlled Format String. Published 2009-09-22.

Is CVE-2009-3294 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Microsoft Windows 7

CVE-2009-3294

The popen API function in TSRM/tsrm_win32.c in PHP before 5.2.11 and 5.3.x before 5.3.1, when running on certain Windows operating systems, allows context-dependent attackers to cause a denial of service (crash) via a crafted (1) "e" or (2) "er" string in the second argument (aka mode), possibly related to the _fdopen function in the Microsoft C runtime library. NOTE: this might not cross privilege boundaries except in rare cases in which the mode argument is accessible to an attacker outside of an application that uses the popen function.

Published 2009-09-22 · last modified 2026-06-16.

CVSS v2 metric

CVSS v2 base score 5.0 (Medium). Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P. This CVE predates CVSS v3 and has no v3 score from NVD.

EPSS exploit prediction

EPSS: 0.027 (85.5th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 86th percentile — 85.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.027 · newest: 0.027 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-134 — Use of Externally-Controlled Format String

Public proof-of-concept exploits

Live-Hack-CVE/CVE-2009-3294

References

www.php.net/ChangeLog-5.php (Vendor Advisory)
www.openwall.com/lists/oss-security/2009/11/20/3 (mailing-list, Mailing List)
news.php.net/php.announce/79 (Vendor Advisory, mailing-list)
www.php.net/releases/5_2_11.php (Patch, Vendor Advisory)
www.php.net/ChangeLog-5.php (Vendor Advisory)
www.openwall.com/lists/oss-security/2009/11/20/2 (mailing-list, Mailing List)
bugs.php.net/bug.php (Exploit, Vendor Advisory)
www.php.net/releases/5_3_1.php (Vendor Advisory)
www.openwall.com/lists/oss-security/2009/09/20/1 (mailing-list, Patch, Mailing List)
www.osvdb.org/58188 (vdb-entry, Broken Link)

Frequently asked questions

What is CVE-2009-3294?: CVE-2009-3294 is a vulnerability in Microsoft Windows 7, classified under Use of Externally-Controlled Format String. Published 2009-09-22.
Is CVE-2009-3294 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.