Memory disclosure or crash via NUL encoding name
Published May 10, 2026 · Updated May 10, 2026
Out-of-bounds read in PHP 8.4.0 through 8.4.20 and 8.5.0 through 8.5.5 allows attackers to disclose memory or crash PHP via crafted encoding names. mbfl_name2encoding_ex() treats a zero strncasecmp() result as proof of equal-length names, then indexes a shorter global MIME name or alias at the untrusted length. Exploitation requires an application or configuration path that passes an attacker-controlled encoding name containing an embedded NUL byte; the bounded effects are adjacent global-data disclosure or a PHP process crash.
Summary
What happened
Out-of-bounds read in PHP 8.4.0 through 8.4.20 and 8.5.0 through 8.5.5 allows attackers to disclose memory or crash PHP via crafted encoding names. mbfl_name2encoding_ex() treats a zero strncasecmp() result as proof of equal-length names, then indexes a shorter global MIME name or alias at the untrusted length. Exploitation requires an application or configuration path that passes an attacker-controlled encoding name containing an embedded NUL byte; the bounded effects are adjacent global-data disclosure or a PHP process crash.
The record
- CVE
- CVE-2026-6104
- Published
- May 10, 2026
- Updated
- May 10, 2026
- Vendor
- The PHP Group
- Product
- PHP
- Classifications
- CWE-125, T1190
- 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=8.4.* <8.4.21
- Affected versionversion=8.5.* <8.5.6
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
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
- PHP Group embedded-NUL encoding minimal reproducerproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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