CVE-2026-89161: 
MariaDB Server 脆弱性の分析と軽減

CVE-2026-89161 is a memory management vulnerability in PCRE2's JIT matching engine that causes an incorrect free operation when pcre2_jit_match() is called with a match data object that previously held a copied subject (via PCRE2_COPY_MATCHED_SUBJECT from a non-JIT match). All PCRE2 versions before 10.48 are affected, including the 10.48-rc1 release candidate. The vulnerability was published on September 11, 2026, and patched in PCRE2 10.48 released August 31, 2026. It carries a CVSS v3.1 base score of 7.8 (High) per Feedly/NVD, or 7.4 (High) per ENISA (Red Hat Advisory, PCRE2 Release).

The root cause is classified under CWE-590 (Free of Memory Not on the Heap) and CWE-1341 (Multiple Releases of Same Resource or Handle). When pcre2_match() is called with PCRE2_COPY_MATCHED_SUBJECT, it stores a heap-allocated copy of the subject string in the match data object and sets the PCRE2_MD_COPIED_SUBJECT flag. If the same match data object is subsequently passed to pcre2_jit_match(), the fast-path JIT function does not properly handle this pre-existing copied subject — it neither releases the memory (causing a leak) nor clears the flag, leading to an invalid free operation when the match data is later freed. The fix, implemented in PR #937, ensures that pcre2_jit_match() correctly detects and frees any previously copied subject before proceeding (GitHub PR #937, PCRE2 Release).

Successful exploitation can result in memory corruption, information disclosure (memory leak), or denial of service (crash due to invalid free). A local attacker with low privileges and no user interaction required can trigger the incorrect free by crafting an application workflow that reuses a match data object between pcre2_match() with PCRE2_COPY_MATCHED_SUBJECT and pcre2_jit_match(). Given PCRE2's widespread use as a regex library in many applications and operating system components, the vulnerability's scope extends to any software that uses the JIT fast-path matching API in this specific pattern (Red Hat Advisory, Feedly).

There is no public proof-of-concept exploit and no evidence of in-the-wild exploitation at this time. The EPSS score is approximately 0.11%, reflecting low near-term exploitation probability. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. NVD's SSVC assessment classifies it as non-automatable with no known exploitation (Red Hat Advisory, GitHub PR #937).

The primary remediation is to upgrade PCRE2 to version 10.48 or later, which includes the fix merged in PR #937. Linux distribution vendors including SUSE and openSUSE have released updated packages (e.g., SUSE-SU-2026:4201-1 and SUSE-SU-2026:4241-1). Organizations should prioritize patching systems where local users have access to applications using PCRE2 with JIT compilation enabled, particularly those that reuse match data objects across JIT and non-JIT match calls. No configuration-based workaround is available other than disabling JIT compilation in PCRE2 if upgrading is not immediately possible (PCRE2 Release, SUSE Advisory).

Red Hat has published a security advisory tracking this CVE, and SUSE issued security updates for affected packages shortly after disclosure. The oss-security mailing list carried a notification (seclists.org/oss-sec/2026/q3/723). Microsoft also acknowledged the vulnerability via its Security Response Center. Community reaction has been measured, consistent with a library-level memory management bug that requires specific API usage patterns to trigger (Red Hat Advisory, SUSE Advisory).