A vulnerability in PHP could allow an unauthenticated, remote attacker to completely compromise a targeted system.
The vulnerability exists in the ext/mbstring/oniguruma/regcomp.c, ext/mbstring/oniguruma/regexec.c, ext/mbstring/oniguruma/regparse.c, ext/mbstring/oniguruma/enc/unicode.c, and ext/mbstring/oniguruma/src/utf32_be.c source code files, and is due to improper memory operations that are performed by the affected software when handling mbstring regular expression functions. An attacker could exploit the vulnerability by sending a crafted multibyte regular expression that contains invalid multibyte sequences to the targeted system. A successful exploit could cause a heap-based buffer over-read condition, which could allow the attacker to completely compromise the targeted system.
Proof-of-concept (PoC) code that demonstrates an exploit of this vulnerability is publicly available.
PHP has confirmed the vulnerability and released software updates.
To exploit this vulnerability, the attacker must send a crafted multibyte regular
expression to the targeted system, making exploitation more difficult in
environments that restrict network access from untrusted sources.
Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
Administrators are advised to run both firewall and antivirus
applications to minimize the potential of inbound and outbound threats.
Administrators may consider using IP-based access control lists
(ACLs) to allow only trusted systems to access the affected systems.
Administrators can help protect affected systems from external attacks by using a solid firewall strategy.
Administrators are advised to monitor affected systems.
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Cisco Multivendor Vulnerability Alerts respond to vulnerabilities identified in third-party vendors' products. These alerts contain information compiled from diverse sources and provide comprehensive technical descriptions, objective analytical assessments, workarounds and practical safeguards, and links to vendor advisories and patches.