Vulnerability Details CVE-2026-6104
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 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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.0
EPSS Ranking 7.8%
CVSS Severity
CVSS v3 Score 9.1
Products affected by CVE-2026-6104
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cpe:2.3:a:php:php:8.4.0
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cpe:2.3:a:php:php:8.4.1
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cpe:2.3:a:php:php:8.4.10
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cpe:2.3:a:php:php:8.4.11
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cpe:2.3:a:php:php:8.4.12
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cpe:2.3:a:php:php:8.4.13
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cpe:2.3:a:php:php:8.4.14
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cpe:2.3:a:php:php:8.4.15
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cpe:2.3:a:php:php:8.4.16
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cpe:2.3:a:php:php:8.4.17
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cpe:2.3:a:php:php:8.4.18
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cpe:2.3:a:php:php:8.4.19
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cpe:2.3:a:php:php:8.4.2
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cpe:2.3:a:php:php:8.4.20
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cpe:2.3:a:php:php:8.4.3
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cpe:2.3:a:php:php:8.4.4
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cpe:2.3:a:php:php:8.4.5
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cpe:2.3:a:php:php:8.4.6
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cpe:2.3:a:php:php:8.4.7
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cpe:2.3:a:php:php:8.4.8
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cpe:2.3:a:php:php:8.4.9
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cpe:2.3:a:php:php:8.5.0
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cpe:2.3:a:php:php:8.5.1
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cpe:2.3:a:php:php:8.5.2
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cpe:2.3:a:php:php:8.5.3
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cpe:2.3:a:php:php:8.5.4
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cpe:2.3:a:php:php:8.5.5