Summary

• A vulnerability in Perl could allow an unauthenticated, remote attacker to access sensitive information on a targeted system.

  The vulnerability exists in the S_grok_bslash_N function, as defined in the regcomp.c source code file, and is due to improper memory operations that are performed by the affected software when handling regular expressions. An attacker could exploit the vulnerability by sending a crafted regular expression that submits malicious input to the Perl interpreter. A successful exploit could cause a heap-based buffer overflow condition, which could allow the attacker to access sensitive information.

  Proof-of-concept code that demonstrates an exploit of this vulnerability is publicly available.

  Perl.org has confirmed the vulnerability and released software updates.

Analysis

• To exploit this vulnerability, the attacker must send a crafted regular expression to the targeted system, making exploitation more difficult in environments that restrict network access from untrusted sources.

Safeguards

• Administrators are advised to apply the appropriate updates.

  Administrators are advised to allow only trusted users to have network access.

  Administrators can help protect affected systems from external attacks by using a solid firewall strategy.

  Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.

  Administrators are advised to monitor affected systems.

Vendor Announcements

• Perl.org has published a bug report at the following link: Bug #133192

Fixed Software

• Perl.org has released software updates at the following link: Perl Download

Revision History

• Version	Description	Section	Date
  1	Initial public release.	—	2018-December-03

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Affected Products

• The security vulnerability applies to the following combinations of products.
  
  

  Primary Products
  Perl.org	Perl	5.26 (.0, .1, .2) | 5.28 (.0)

  Associated Products