PHP 8.2-8.5: signed char to ctype triggers DoS in urldecode
CVE-2026-7258 Published on May 10, 2026
Out-of-bounds read in urldecode() on NetBSD
In PHP versions 8.2.* before 8.2.31, 8.3.* before 8.3.31, 8.4.* before 8.4.21, and 8.5.* before 8.5.6, some functions, including urldecode(), pass signed char to ctype functions (like isxdigit()). On the systems with default signed char and optimized table-lookup ctype functions - such as NetBSD - this can lead to accessing array with negative offset, which can trigger a denial of service.
Weakness Type
Out-of-bounds Read
The software reads data past the end, or before the beginning, of the intended buffer. Typically, this can allow attackers to read sensitive information from other memory locations or cause a crash. A crash can occur when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string. The expected sentinel might not be located in the out-of-bounds memory, causing excessive data to be read, leading to a segmentation fault or a buffer overflow. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent read operation then produces undefined or unexpected results.
Products Associated with CVE-2026-7258
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Affected Versions
PHP Group PHP:- Version 8.2.* and below 8.2.31 is affected.
- Version 8.3.* and below 8.3.31 is affected.
- Version 8.4.* and below 8.4.21 is affected.
- Version 8.5.* and below 8.5.6 is affected.