strongSwan VPN's charon server prior to version 5.6.3 does not check packet length and may allow buffer underflow, resulting in denial of service.
CWE-124: Buffer Underwrite ('Buffer Underflow') - CVE-2018-5388
In stroke_socket.c, a missing packet length check could allow a buffer underflow, which may lead to resource exhaustion and denial of service while reading from the socket.
According to the vendor, an attacker must typically have local root permissions to access the socket. However, other accounts and groups such as the vpn group (if capability dropping in enabled, for example) may also have sufficient permissions, but this configuration does not appear to be the default behavior.
A remote attacker with local user credentials (possibly a normal user in the vpn group, or root) may be able to underflow the buffer and cause a denial of service.
Apply an update
StrongSwan version 5.6.3 and above contain a patch for this issue.
strongswan-5.6.3 addressing a number of bugs and vulnerabilities was released on 2018/05/28. Can you please push to the stable tree?
Please bump this version and target for stable soon
Added to an existing GLSA request.
This issue was resolved and addressed in
GLSA 201811-16 at https://security.gentoo.org/glsa/201811-16
by GLSA coordinator Aaron Bauman (b-man).