dbcve.org
FedoraOperating system · Fedoraproject

CVE-2015-8389

CRITICAL · 9.8 CVSS v3.1 Published 2015-12-02
Fix available
A fix is available. Upgrade to 5.5.32 / 5.6.18 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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
PCRE before 8.38 mishandles the /(?:|a|){100}x/ pattern and related patterns, which allows remote attackers to cause a denial of service (infinite recursion) or possibly have unspecified other impact via a crafted regular expression, as demonstrated by a JavaScript RegExp object encountered by Konqueror.

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 · high confidence

PCRE library before version 8.38 contains a regex parsing vulnerability where certain patterns (such as /(?:|a|){100}x/) cause infinite recursion due to improper handling of empty alternations combined with quantifiers. This ReDoS (Regular Expression Denial of Service) vulnerability can be triggered by passing crafted regex patterns to applications using the vulnerable PCRE library, as demonstrated via JavaScript RegExp objects in Konqueror.

MitigationUpgrade PCRE library to version 8.38 or later across all affected systems. Audit applications that accept user-supplied regex input and implement timeouts or resource limits for regex operations to prevent similar DoS conditions.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

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
FedoraOperating system
Affected:= 22
PHPApplication
Affected:>= 5.5.0, < 5.5.32>= 5.6.0, < 5.6.18>= 7.0.0, < 7.0.3
Perl Compatible Regular Expression LibraryApplication
Affected:<= 8.37

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed PCRE library version
    Run `pcre-config --version` or check the library file with `ls -la /usr/lib/libpcre*` and examine version info with `strings` or check package manager with `rpm -q pcre` or `dpkg -l libpcre3`
    Affected if Version is 8.37 or lower
  2. Identify PHP version if used
    Run `php -v` to get PHP version, or check via package manager with `rpm -q php` or `dpkg -l php*`
    Affected if PHP version is 5.5.0-5.5.31, 5.6.0-5.17.18, or 7.0.0-7.0.2
  3. Check Fedora version
    Run `cat /etc/fedora-release` or `rpm -q fedora-release`
    Affected if Running Fedora 22 specifically
  4. Determine if applications accept user-supplied regex
    Audit application source code or configuration for usage of PCRE functions (such as preg_match, preg_match_all in PHP, or regex functions in other languages) with input that could be controlled by users. Search for patterns like preg_match with variables in the regex pattern argument.
    Affected if Applications accept unsanitized user input to be used as regex patterns in PCRE-based functions
  5. Test for vulnerability with proof-of-concept pattern
    If using PHP, create a test script with the pattern `/(?:|a|){100}x/` passed to preg_match and observe if it causes excessive CPU usage or hangs. In other languages using PCRE, test the same pattern. Monitor process with `time` command or observe for hang condition.
    Affected if The pattern causes the application to hang, crash, or exhibit excessive resource consumption

You are affected if your PCRE library version is 8.37 or lower, or if you run the specific vulnerable PHP versions, AND your applications pass user-supplied input to PCRE regex functions without validation.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 5.5.32 / 5.6.18 / 7.0.3 or later
Fixed in 5.5.325.6.187.0.3
Interim mitigation

Upgrade PCRE library to version 8.38 or later across all affected systems. Audit applications that accept user-supplied regex input and implement timeouts or resource limits for regex operations to prevent similar DoS conditions.

Recommended fix High confidence

PCRE 8.38 or later (PHP 5.5.32+/5.6.18+/7.0.3+)

  1. Upgrade PCRE library to version 8.38 or later
  2. For PHP installations that bundle PCRE: upgrade PHP to version 5.5.32 or later, 5.6.18 or later, or 7.0.3 or later
  3. For systems with separate PCRE package (e.g., Fedora 22): update the pcre package to the version containing PCRE 8.38 or newer
  4. After upgrading, restart any services that use PCRE or PHP to ensure the new library is loaded
  5. Verify the fix by testing that the vulnerable regex pattern no longer causes infinite recursion
Caveat Regular expression behavior may have subtle differences in edge cases between PCRE versions; test critical regex patterns after upgrade

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

Fix this in Fedora Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing8.0 h
  • Review / QA4.0 h
30.0 hours of engineering $5,280
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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-2015-8389 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data