Interpreter crash via negative ctype table index
Published May 10, 2026 · Updated May 10, 2026
Out-of-bounds read in PHP allows remote attackers to crash the interpreter by passing a non-ASCII byte to urldecode(). In php_url_decode_ex() in ext/standard/url.c, signed char bytes reach isxdigit(), where sign extension can produce a negative table index. Exploitation requires PHP 8.2 before 8.2.31, 8.3 before 8.3.31, 8.4 before 8.4.21, or 8.5 before 8.5.6 on NetBSD-like ctype implementations; the demonstrated result is a PHP process segfault.
Summary
What happened
Out-of-bounds read in PHP allows remote attackers to crash the interpreter by passing a non-ASCII byte to urldecode(). In php_url_decode_ex() in ext/standard/url.c, signed char bytes reach isxdigit(), where sign extension can produce a negative table index. Exploitation requires PHP 8.2 before 8.2.31, 8.3 before 8.3.31, 8.4 before 8.4.21, or 8.5 before 8.5.6 on NetBSD-like ctype implementations; the demonstrated result is a PHP process segfault.
The record
- CVE
- CVE-2026-7258
- Published
- May 10, 2026
- Updated
- May 10, 2026
- Vendor
- The PHP Group
- Product
- PHP
- Classifications
- CWE-125, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 10, 2026CVE publishedPublication date reported by the CVE source.
- May 10, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=8.2.* <8.2.31
- Affected versionversion=8.3.* <8.3.31
- Affected versionversion=8.4.* <8.4.21
- Affected versionversion=8.5.* <8.5.6
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- urldecode non-ASCII byte crash reproducerproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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