CVE-2026-6104
Published: 10 May 2026
Summary
CVE-2026-6104 is a medium-severity Out-of-bounds Read (CWE-125) vulnerability in Php Php. Its CVSS base score is 6.3 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 37.2th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-28979
Vulnerability details
In PHP versions 8.4.* before 8.4.21 and 8.5.* before 8.5.6, when an encoding name containing an embedded NUL byte is passed to mb_convert_encoding() or related mbstring functions, the code incorrectly assumes that when strncasecmp() returns 0 it means the strings…
more
have the same length. This can lead to out-of-bounds read of global memory, potentially causing a crash or information disclosure or crash. Affected functions include mb_convert_encoding(), mb_detect_encoding(), mb_convert_variables(), and mb_detect_order(), as well as the mbstring.detect_order and mbstring.http_output INI settings.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
OOB read in PHP mbstring enables exploitation of public-facing web apps (T1190) for info disclosure or DoS via crafted encoding inputs; no direct RCE or other mappings.
Affected Assets
Mitigating Controls
No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.