SB2021062148 - Ubuntu update for apache2

Description

This security bulletin contains information about 4 secuirty vulnerabilities.

1) Stack-based buffer overflow (CVE-ID: CVE-2020-35452)

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

The vulnerability exists due to a boundary error when processing Digest nounces in mod_auth_digest. A remote unauthenticated attacker can send a specially crafted HTTP request, trigger stack overflow by one nul byte and crash the server.

2) NULL pointer dereference (CVE-ID: CVE-2021-26690)

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

The vulnerability exists due to a NULL pointer dereference error in mod_session. A remote attacker can pass specially crafted data to the application and perform a denial of service (DoS) attack.

3) NULL pointer dereference (CVE-ID: CVE-2021-26691)

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

The vulnerability exists due to a NULL pointer dereference error in mod_session. A a malicious backend server or SessionHeader can trigger a denial of service (DoS) condition.

4) Input validation error (CVE-ID: CVE-2021-30641)

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to incorrect parsing of Apache configuration files. An unexpected section could be matched with 'MergeSlashes OFF' option, leading to a potential security issue.

Remediation

Install update from vendor's website.

References

• https://ubuntu.com/security/notices/USN-4994-2