SB2019090101 - Gentoo update for Dovecot

Description

This security bulletin contains information about 2 vulnerabilities.

1) Input validation error (CVE-ID: CVE-2019-10691)

CWE-ID: CWE-20 - Improper input validation

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote attacker to perform denial of service (DoS) attack.

The vulnerability exists due to improper input validation of user-supplied characters in UTF-8 encoding within the JSON encoder. A remote unauthenticated attacker can supply a specially crafted string that contains invalid UTF-8 characters via a username during authentication process or via “From” or “Subject” headers in an email (if OX push notification driver is enabled) and crash the affected server.

Successful exploitation of the vulnerability will result in denial of service (DoS) attack.

2) Out-of-bounds write (CVE-ID: CVE-2019-11500)

CWE-ID: CWE-787 - Out-of-bounds write

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/U:Amber

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a boundary error within IMAP and ManageSieve protocol implementation the when scanning data in quoted strings. A remote attacker can send a specially crafted request to the affected server, trigger out-of-bounds write and execute arbitrary code on the target system.

Exploitation example:

perl -e 'print "a id (\"foo\" \"".("x"x1021)."\\A\" \"bar\"
\"\000".("x"x1020)."\\A\")\n"' | nc localhost 143

Remediation

Install update from vendor's website.

References

• https://security.gentoo.org/
• https://security.gentoo.org/glsa/201908-29