CVE-2019-12519

Name of the Vulnerable Software and Affected Versions: Squid versions through 4.7

Description: The issue is related to the ESIExpression::Evaluate function in the Squid proxy server, which is associated with a buffer data boundary overflow. This could allow a remote attacker to access confidential data, compromise its integrity, and cause a denial of service. The problem arises when handling the esi:when tag with ESI enabled, as the ESIExpression::Evaluate function uses a fixed stack buffer without checking for potential overflows when adding new members to the stack.

Recommendations: For Squid versions through 4.7, consider disabling the ESI feature to prevent exploitation until a patch is available. As a temporary workaround, restrict access to the ESIExpression::Evaluate function to minimize the risk of exploitation. Avoid using the esi:when tag in configurations where ESI is enabled until the issue is resolved.