CVE-2008-5557

CVE-2008-5557 is a critical-severity vulnerability in Php with a CVSS 2.0 base score of 10.0. 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-119.

Key facts

• Severity: Critical (CVSS 2.0 base score 10.0)
• EPSS exploit prediction: 7% (94th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-119
• Affected product: Php
• Published: 2008-12-23
• Last modified: 2026-06-16

Description

Heap-based buffer overflow in ext/mbstring/libmbfl/filters/mbfilter_htmlent.c in the mbstring extension in PHP 4.3.0 through 5.2.6 allows context-dependent attackers to execute arbitrary code via a crafted string containing an HTML entity, which is not properly handled during Unicode conversion, related to the (1) mb_convert_encoding, (2) mb_check_encoding, (3) mb_convert_variables, and (4) mb_parse_str functions.

Frequently asked questions

What is CVE-2008-5557?

Heap-based buffer overflow in ext/mbstring/libmbfl/filters/mbfilter_htmlent.c in the mbstring extension in PHP 4.3.0 through 5.2.6 allows context-dependent attackers to execute arbitrary code via a crafted string containing an HTML entity, which is not properly handled during Unicode conversion, related to the (1) mb_convert_encoding, (2) mb_check_encoding, (3) mb_convert_variables, and (4) mb_parse_str functions.

How severe is CVE-2008-5557?

CVE-2008-5557 has a CVSS 2.0 base score of 10.0, rated critical severity.

Is CVE-2008-5557 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (94th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2008-5557?

CVE-2008-5557 primarily affects Php. In total, 49 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2008-5557?

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-2008-5557 published?

CVE-2008-5557 was published on 2008-12-23 and last updated on 2026-06-16.

References

• http://archives.neohapsis.com/archives/fulldisclosure/2008-12/0477.html
• http://bugs.php.net/bug.php?id=45722
• http://cvs.php.net/viewvc.cgi/php-src/ext/mbstring/libmbfl/filters/mbfilter_htmlent.c?r1=1.7&r2=1.8
• http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=c02029444
• http://lists.apple.com/archives/security-announce/2009/May/msg00002.html
• http://lists.opensuse.org/opensuse-security-announce/2009-02/msg00002.html
• http://lists.opensuse.org/opensuse-security-announce/2009-04/msg00003.html
• http://marc.info/?l=bugtraq&m=124654546101607&w=2
• http://marc.info/?l=bugtraq&m=125631037611762&w=2
• http://secunia.com/advisories/34642
• http://secunia.com/advisories/35003
• http://secunia.com/advisories/35074
• http://secunia.com/advisories/35306
• http://secunia.com/advisories/35650
• http://securitytracker.com/id?1021482
• http://support.apple.com/kb/HT3549
• http://wiki.rpath.com/Advisories:rPSA-2009-0035
• http://www.debian.org/security/2009/dsa-1789
• http://www.mandriva.com/security/advisories?name=MDVSA-2009:045
• http://www.php.net/ChangeLog-5.php#5.2.7
• http://www.redhat.com/support/errata/RHSA-2009-0350.html
• http://www.securityfocus.com/archive/1/501376/100/0/threaded
• http://www.securityfocus.com/bid/32948
• http://www.us-cert.gov/cas/techalerts/TA09-133A.html
• http://www.vupen.com/english/advisories/2009/1297
• https://exchange.xforce.ibmcloud.com/vulnerabilities/47525
• https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10286
• https://www.redhat.com/archives/fedora-package-announce/2009-May/msg01451.html
• https://www.redhat.com/archives/fedora-package-announce/2009-May/msg01465.html

Affected products (49)

• cpe:2.3:a:php:php:4.3.0:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.3.1:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.3.2:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.3.3:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.3.4:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.3.5:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.3.6:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.3.7:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.3.8:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.3.9:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.3.10:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.3.11:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.4.0:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.4.1:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.4.2:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.4.3:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.4.4:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.4.5:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.4.6:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.4.7:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.4.8:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:4.4.9:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.0.0:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.0.0:beta1:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.0.0:beta2:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.0.0:beta3:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.0.0:beta4:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.0.0:rc1:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.0.0:rc2:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.0.0:rc3:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.0.1:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.0.2:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.0.3:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.0.4:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.0.5:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.1.0:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.1.1:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.1.2:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.1.3:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:5.1.4:*:*:*:*:*:*:*

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• CVE-2011-3268 — Critical (CVSS 10.0): Buffer overflow in the crypt function in PHP before 5.3.7 allows context-dependent attackers to have an unspecified…
• CVE-2009-4143 — Critical (CVSS 10.0): PHP before 5.2.12 does not properly handle session data, which has unspecified impact and attack vectors related to (1)…
• CVE-2008-2051 — Critical (CVSS 10.0): The escapeshellcmd API function in PHP before 5.2.6 has unknown impact and context-dependent attack vectors related to…

All CVEs affecting Php →

Other CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) vulnerabilities

• CVE-2026-2778 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component. This vulnerability was fixed in…
• CVE-2026-2776 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software. This vulnerability…
• CVE-2025-1866 — Critical (CVSS 10.0): Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerability in warmcat libwebsockets allows…
• CVE-2022-27625 — Critical (CVSS 10.0): A vulnerability regarding improper restriction of operations within the bounds of a memory buffer is found in the…
• CVE-2022-27624 — Critical (CVSS 10.0): A vulnerability regarding improper restriction of operations within the bounds of a memory buffer is found in the…
• CVE-2020-11896 — Critical (CVSS 10.0): The Treck TCP/IP stack before 6.0.1.66 allows Remote Code Execution, related to IPv4 tunneling.

Browse all CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

• 222.99.52.202 (ipv4-addr)
• 90.160.135.217 (ipv4-addr)
• 76.133.97.153 (ipv4-addr)
• 62.36.19.42 (ipv4-addr)
• 62.36.19.41 (ipv4-addr)
• 171.100.156.38 (ipv4-addr)