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LinuxOperating system · Oracle

CVE-2015-8391

CRITICAL · 9.8 CVSS v3.1 Published 2015-12-02
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
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
The pcre_compile function in pcre_compile.c in PCRE before 8.38 mishandles certain [: nesting, which allows remote attackers to cause a denial of service (CPU consumption) 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

The PCRE library before version 8.38 contains a vulnerability in the pcre_compile function where certain nested POSIX character classes ([:) are mishandled during regular expression compilation. This causes the regex engine to enter an inefficient processing path, leading to excessive CPU consumption (denial of service) or potentially other unspecified impact when processing specially crafted regular expressions.

MitigationUpgrade PCRE library to version 8.38 or later to patch the vulnerable regex compilation code. If upgrading is not immediately feasible, consider input validation or rate limiting on regex operations to mitigate DoS risk.

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
LinuxOperating system
Affected:= 7
FedoraOperating system
Affected:= 22
Enterprise Linux DesktopOperating system
Affected:= 7.0
Enterprise Linux EusOperating system
Affected:= 7.2= 7.3= 7.4= 7.5= 7.6= 7.7
Enterprise Linux ServerOperating system
Affected:= 7.0
Enterprise Linux Server AusOperating system
Affected:= 7.2= 7.3= 7.4= 7.6= 7.7
Enterprise Linux Server TusOperating system
Affected:= 7.2= 7.3= 7.6= 7.7
Enterprise Linux WorkstationOperating system
Affected:= 7.0

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 command: pcre --version or pcre2 --version. On RPM-based systems, also try: rpm -q pcre or rpm -q pcre2
    Affected if The version number returned is lower than 8.38 (e.g., 8.x before 8.38, or any 7.x version)
  2. Check PCRE package version via system package manager
    On RHEL/CentOS/OEL: rpm -qa | grep -i pcre. On Fedora: dnf list installed | grep -i pcre
    Affected if The installed package version shown is less than 8.38- (for example, pcre-8.x where x < 38, or any pcre-7.x package)
  3. Verify PCRE library file version
    Check the shared library file directly: ls -la /lib*/libpcre* and readlink -f /lib*/libpcre*.so.*. Alternatively, use: strings /lib*/libpcre*.so.* | grep -E '^8\.[0-9]+$' | sort -V
    Affected if The library file version is 8.37, 8.36, 7.x, or any version below 8.38
  4. Confirm application uses PCRE for regex processing
    Identify applications that link to PCRE: ldd <application_binary> | grep pcre. Check application config files for regex usage patterns
    Affected if The application links against a vulnerable PCRE library version (below 8.38) and processes user-supplied or external regex patterns

Your environment is affected if the installed PCRE library version (pcre or pcre2) is 8.38 or earlier, and your applications process regular expressions that could include nested POSIX character classes ([:).

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade PCRE library to version 8.38 or later to patch the vulnerable regex compilation code. If upgrading is not immediately feasible, consider input validation or rate limiting on regex operations to mitigate DoS risk.

Recommended fix High confidence

PCRE 8.38 or later

  1. 1. Identify the PCRE library package installed on the system (e.g., using 'rpm -qa | grep pcre' or 'dpkg -l | grep pcre')
  2. 2. For RHEL/CentOS systems: run 'yum update pcre' or 'dnf update pcre' to apply the security update
  3. 3. For Fedora systems: run 'dnf update pcre' to apply the updated package
  4. 4. After updating, verify the new PCRE version is 8.38 or later using 'pcre-config --version'
  5. 5. Restart any services that use PCRE to ensure they load the updated library
  6. 6. Test that applications using regular expressions still function correctly
Caveat Upgrading PCRE is generally safe; however, applications compiled against the old PCRE version may need to be recompiled if there are ABI changes

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

Fix this in Linux Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2015-8391 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