CVE-2009-5155: In the GNU C Library (aka glibc or libc6) before 2.28, parse_reg_exp in posix/regcomp.c misparses alternati...

Security readout for executives and security teams

CVE-2009-5155 is a GNU C Library regex parsing flaw fixed before glibc 2.28. A crafted regular-expression match can make an affected application exit or return an incorrect match result. Business impact is mainly service disruption or bad logic decisions in software that relies on glibc regex behavior. Exposure is most likely on Linux systems or vendor appliances using glibc/libc6 before 2.28, especially where applications compile or execute regexes influenced by users, files, requests, or external data. Handle through normal vulnerability management unless exposed services accept untrusted regex input or have crash evidence. The main concern is availability and correctness, not documented remote code execution. Mitigation focus: Upgrade glibc/libc6 to 2.28 or a vendor-supported fixed backport.; Check Linux distribution, NetApp, and F5 advisories for product-specific remediation.; Prioritize internet-facing services that process untrusted regex patterns or regex-driven rules..

Prepared

Jun 6, 2026, 21:46 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.