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Fencer Vulns
critical 10.0

CVE-2008-5557 in the critical feed json

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 c…

published 2008-12-23 17 y ago modified 2026-06-16 4 mo ago also EUVD-2008-5532

cvss
10.0
version 2.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
7.4%
EPSS 7.4% chance of exploitation in 30 days, percentile 94%
public exploits
0
none known

Summary

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.

Patch / fix

  • php RHEL 2 APPLICATION_STACK 5.2.6-4.el5s2
  • php-gd RHEL 2 APPLICATION_STACK 5.2.6-4.el5s2
  • php-cli RHEL 2 APPLICATION_STACK 5.2.6-4.el5s2
  • php-dba RHEL 2 APPLICATION_STACK 5.2.6-4.el5s2
  • php-pdo RHEL 2 APPLICATION_STACK 5.2.6-4.el5s2
  • php-xml RHEL 2 APPLICATION_STACK 5.2.6-4.el5s2
  • php-imap RHEL 2 APPLICATION_STACK 5.2.6-4.el5s2
  • php-ldap RHEL 2 APPLICATION_STACK 5.2.6-4.el5s2

red hat advisories RHSA-2009:0350RHSA-2009:0338RHSA-2009:0337

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2008-5557 updated

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

  • Red Hat Desktop version 3 php 4.3.2-51.ent, php-imap 4.3.2-51.ent, php-ldap 4.3.2-51.ent, php-odbc 4.3.2-51.ent, php-mysql 4.3.2-51.ent, php-pgsql 4.3.2-51.ent
    fixed: vendor fix RHSA-2009:0337
  • Red Hat Enterprise Linux (v. 5 server) php 5.1.6-23.2.el5_3, php-gd 5.1.6-23.2.el5_3, php-cli 5.1.6-23.2.el5_3, php-dba 5.1.6-23.2.el5_3, php-pdo 5.1.6-23.2.el5_3, php-xml 5.1.6-23.2.el5_3, +12 more
    fixed: vendor fix RHSA-2009:0338
  • Red Hat Enterprise Linux AS version 3 php 4.3.2-51.ent, php-imap 4.3.2-51.ent, php-ldap 4.3.2-51.ent, php-odbc 4.3.2-51.ent, php-mysql 4.3.2-51.ent, php-pgsql 4.3.2-51.ent Red Hat Enterprise Linux AS version 4 php 4.3.9-3.22.15, php-gd 4.3.9-3.22.15, php-imap 4.3.9-3.22.15, php-ldap 4.3.9-3.22.15, php-odbc 4.3.9-3.22.15, php-pear 4.3.9-3.22.15, +7 more Red Hat Enterprise Linux Desktop version 4 php 4.3.9-3.22.15, php-gd 4.3.9-3.22.15, php-imap 4.3.9-3.22.15, php-ldap 4.3.9-3.22.15, php-odbc 4.3.9-3.22.15, php-pear 4.3.9-3.22.15, +7 more
    fixed: vendor fix RHSA-2009:0337
  • Red Hat Enterprise Linux Desktop Workstation (v. 5 client) php 5.1.6-23.2.el5_3, php-gd 5.1.6-23.2.el5_3, php-cli 5.1.6-23.2.el5_3, php-dba 5.1.6-23.2.el5_3, php-pdo 5.1.6-23.2.el5_3, php-xml 5.1.6-23.2.el5_3, +12 more
    fixed: vendor fix RHSA-2009:0338
  • Red Hat Enterprise Linux ES version 3 php 4.3.2-51.ent, php-imap 4.3.2-51.ent, php-ldap 4.3.2-51.ent, php-odbc 4.3.2-51.ent, php-mysql 4.3.2-51.ent, php-pgsql 4.3.2-51.ent Red Hat Enterprise Linux ES version 4 php 4.3.9-3.22.15, php-gd 4.3.9-3.22.15, php-imap 4.3.9-3.22.15, php-ldap 4.3.9-3.22.15, php-odbc 4.3.9-3.22.15, php-pear 4.3.9-3.22.15, +7 more Red Hat Enterprise Linux WS version 3 php 4.3.2-51.ent, php-imap 4.3.2-51.ent, php-ldap 4.3.2-51.ent, php-odbc 4.3.2-51.ent, php-mysql 4.3.2-51.ent, php-pgsql 4.3.2-51.ent Red Hat Enterprise Linux WS version 4 php 4.3.9-3.22.15, php-gd 4.3.9-3.22.15, php-imap 4.3.9-3.22.15, php-ldap 4.3.9-3.22.15, php-odbc 4.3.9-3.22.15, php-pear 4.3.9-3.22.15, +7 more
    fixed: vendor fix RHSA-2009:0337

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

7.37% chance of exploitation in the next 30 days, higher than 94% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • cvs.php.net http://cvs.php.net/viewvc.cgi/php-src/ext/mbstring/libmbfl/filters/mbfilter_htmlent.c?r1=1.7&r2=1.8 referenced PoC, tagged "exploit" by a source, unverified
  • bugs.php.net http://bugs.php.net/bug.php?id=45722 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 2.0 10.0 AV:N/AC:L/Au:N/C:C/I:C/A:C

Classification

Weakness
  • CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.