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PHPApplication

CVE-2019-9023

CRITICAL · 9.8 CVSS v3.0 Published 2019-02-22
Fix available
A fix is available. Upgrade to 5.6.40 / 7.1.26 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
An issue was discovered in PHP before 5.6.40, 7.x before 7.1.26, 7.2.x before 7.2.14, and 7.3.x before 7.3.1. A number of heap-based buffer over-read instances are present in mbstring regular expression functions when supplied with invalid multibyte data. These occur in ext/mbstring/oniguruma/regcomp.c, ext/mbstring/oniguruma/regexec.c, ext/mbstring/oniguruma/regparse.c, ext/mbstring/oniguruma/enc/unicode.c, and ext/mbstring/oniguruma/src/utf32_be.c when a multibyte regular expression pattern contains invalid multibyte sequences.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-125

The code reads past the end (or before the start) of a buffer, returning memory that was never meant to be exposed. Attackers use it to leak secrets like keys or to defeat memory-protection defences. Remediation is validating indices and lengths before every read.

General guidance for the out-of-bounds read class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
PHPApplication
Affected:< 5.6.40>= 7.0.0, < 7.1.26>= 7.2.0, < 7.2.14>= 7.3.0, < 7.3.1
Debian LinuxOperating system
Affected:= 9.0
Ubuntu LinuxOperating system
Affected:= 12.04= 14.04= 16.04
Storage Automation StoreApplication
Affected:all versions
LeapOperating system
Affected:= 42.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.6.40 / 7.1.26 / 7.2.14 or later
Fixed in 5.6.407.1.267.2.14
Vendor patch bugs.php.net →
Recommended fix High confidence

PHP 5.6.40, 7.1.26, 7.2.14, or 7.3.1 (choose the appropriate version within your current major.minor branch)

  1. 1. Identify the currently installed PHP version by running 'php -v' or 'phpinfo()'
  2. 2. For PHP 5.6.x: upgrade to PHP 5.6.40 or later
  3. 3. For PHP 7.0.x - 7.1.x: upgrade to PHP 7.1.26 or later
  4. 4. For PHP 7.2.x: upgrade to PHP 7.2.14 or later
  5. 5. For PHP 7.3.x: upgrade to PHP 7.3.1 or later
  6. 6. After upgrading, restart any PHP-enabled services (Apache, PHP-FPM, Nginx, etc.) to load the new version
  7. 7. Verify the fix by confirming the PHP version matches one of the fixed releases and that mbstring regex functions handle invalid multibyte data correctly
Caveat Minor version upgrades within the same major version typically have minimal breaking changes; however, test critical mbstring regex functionality after upgrading

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $3,550. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2019-9023 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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