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CVE-2008-5557

27
FAUCET Score

CVE-2008-5557 describes a heap-based buffer overflow vulnerability in the mbstring extension of PHP versions 4.3.0 through 5.2.6. This flaw allows remote attackers to execute arbitrary code by supplying a specially crafted string containing an HTML entity to functions like mb_convert_encoding or mb_check_encoding, which mishandle Unicode conversion. With a CVSS score of 10.0, this vulnerability is critical, indicating a network-exploitable attack with no authentication required, leading to complete compromise of confidentiality, integrity, and availability. Despite its high severity, there is no evidence of active exploitation, no known public exploit code (Metasploit, Nuclei, ExploitDB), and minimal community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
4.3.0CPE matchmatch criteria
cpe:2.3:a:php:php:4.3.0:*:*:*:*:*:*:*
4.3.1CPE matchmatch criteria
cpe:2.3:a:php:php:4.3.1:*:*:*:*:*:*:*
4.3.2CPE matchmatch criteria
cpe:2.3:a:php:php:4.3.2:*:*:*:*:*:*:*
4.3.3CPE matchmatch criteria
cpe:2.3:a:php:php:4.3.3:*:*:*:*:*:*:*
4.3.4CPE matchmatch criteria
cpe:2.3:a:php:php:4.3.4:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

10.0HIGH

AV:N/AC:L/Au:N/C:C/I:C/A:C

Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Exploitability Score
10.0
Impact Score
10.0
CvssVersion
2.0

Exploit Intelligence

EPSS Score
7.37%
Probability of exploitation in next 30 days
EPSS Percentile
93.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0737 is in the 90th percentile among its peer group of 51,551 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 3Fixed in: php-0:4.3.2-51.ent
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 4Fixed in: php-0:4.3.9-3.22.15
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: php-0:5.1.6-23.2.el5_3
View patch

Vendor Advisories (1)

redhatCVE-2008-5557Moderate

php: Heap-based buffer overflow in the mbstring extension via crafted string containing a HTML entity (arb code execution)

Aug 5, 2008

References

archives.neohapsis.com / archives/fulldisclosure/2008-12/0477.html
bugs.php.net / bug.php
Exploit
cvs.php.net / viewvc.cgi/php-src/ext/mbstring/libmbfl/filters/mbfilter_htmlent.c
Exploit
h20000.www2.hp.com / bizsupport/TechSupport/Document.jsp
lists.apple.com / archives/security-announce/2009/May/msg00002.html
lists.opensuse.org / opensuse-security-announce/2009-02/msg00002.html
lists.opensuse.org / opensuse-security-announce/2009-04/msg00003.html
marc.info
marc.info
secunia.com / advisories/34642
secunia.com / advisories/35003
secunia.com / advisories/35074
secunia.com / advisories/35306
secunia.com / advisories/35650
securitytracker.com / id
exchange.xforce.ibmcloud.com / vulnerabilities/47525
oval.cisecurity.org / repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10286
support.apple.com / kb/HT3549
redhat.com / archives/fedora-package-announce/2009-May/msg01451.html
redhat.com / archives/fedora-package-announce/2009-May/msg01465.html
wiki.rpath.com / Advisories:rPSA-2009-0035
debian.org / security/2009/dsa-1789
mandriva.com / security/advisories
php.net / ChangeLog-5.php
redhat.com / support/errata/RHSA-2009-0350.html
securityfocus.com / archive/1/501376/100/0/threaded
securityfocus.com / bid/32948
us-cert.gov / cas/techalerts/TA09-133A.html
US Government Resource
vupen.com / english/advisories/2009/1297