Debian DLA-2706-1 : apache2 - LTS security update

critical Nessus Plugin ID 151486
New! Plugin Severity Now Using CVSS v3

The calculated severity for Plugins has been updated to use CVSS v3 by default. Plugins that do not have a CVSS v3 score will fall back to CVSS v2 for calculating severity. Severity display preferences can be toggled in the settings dropdown.

Synopsis

The remote Debian host is missing one or more security-related updates.

Description

The remote Debian 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the dla-2706 advisory.

- In Apache HTTP Server 2.4.0 to 2.4.41, redirects configured with mod_rewrite that were intended to be self-referential might be fooled by encoded newlines and redirect instead to an an unexpected URL within the request URL. (CVE-2020-1927)

- In Apache HTTP Server 2.4.0 to 2.4.41, mod_proxy_ftp may use uninitialized memory when proxying to a malicious FTP server. (CVE-2020-1934)

- Apache HTTP Server versions 2.4.0 to 2.4.46 A specially crafted Digest nonce can cause a stack overflow in mod_auth_digest. There is no report of this overflow being exploitable, nor the Apache HTTP Server team could create one, though some particular compiler and/or compilation option might make it possible, with limited consequences anyway due to the size (a single byte) and the value (zero byte) of the overflow (CVE-2020-35452)

- Apache HTTP Server versions 2.4.0 to 2.4.46 A specially crafted Cookie header handled by mod_session can cause a NULL pointer dereference and crash, leading to a possible Denial Of Service (CVE-2021-26690)

- In Apache HTTP Server versions 2.4.0 to 2.4.46 a specially crafted SessionHeader sent by an origin server could cause a heap overflow (CVE-2021-26691)

- Apache HTTP Server versions 2.4.39 to 2.4.46 Unexpected matching behavior with 'MergeSlashes OFF' (CVE-2021-30641)

- Apache HTTP Server protocol handler for the HTTP/2 protocol checks received request headers against the size limitations as configured for the server and used for the HTTP/1 protocol as well. On violation of these restrictions and HTTP response is sent to the client with a status code indicating why the request was rejected. This rejection response was not fully initialised in the HTTP/2 protocol handler if the offending header was the very first one received or appeared in a a footer. This led to a NULL pointer dereference on initialised memory, crashing reliably the child process. Since such a triggering HTTP/2 request is easy to craft and submit, this can be exploited to DoS the server. This issue affected mod_http2 1.15.17 and Apache HTTP Server version 2.4.47 only. Apache HTTP Server 2.4.47 was never released. (CVE-2021-31618)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Upgrade the apache2 packages.

For Debian 9 stretch, these problems have been fixed in version 2.4.25-3+deb9u10.

See Also

https://security-tracker.debian.org/tracker/source-package/apache2

https://www.debian.org/lts/security/2021/dla-2706

https://security-tracker.debian.org/tracker/CVE-2020-1927

https://security-tracker.debian.org/tracker/CVE-2020-1934

https://security-tracker.debian.org/tracker/CVE-2020-35452

https://security-tracker.debian.org/tracker/CVE-2021-26690

https://security-tracker.debian.org/tracker/CVE-2021-26691

https://security-tracker.debian.org/tracker/CVE-2021-30641

https://security-tracker.debian.org/tracker/CVE-2021-31618

https://packages.debian.org/source/stretch/apache2

Plugin Details

Severity: Critical

ID: 151486

File Name: debian_DLA-2706.nasl

Version: 1.3

Type: local

Agent: unix

Published: 7/9/2021

Updated: 9/24/2021

Dependencies: ssh_get_info.nasl

Risk Information

CVSS Score Source: CVE-2021-26691

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: High

Base Score: 7.5

Temporal Score: 5.5

Vector: AV:N/AC:L/Au:N/C:P/I:P/A:P

Temporal Vector: E:U/RL:OF/RC:C

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: E:U/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:debian:debian_linux:apache2, p-cpe:/a:debian:debian_linux:apache2-bin, p-cpe:/a:debian:debian_linux:apache2-data, p-cpe:/a:debian:debian_linux:apache2-dbg, p-cpe:/a:debian:debian_linux:apache2-dev, p-cpe:/a:debian:debian_linux:apache2-doc, p-cpe:/a:debian:debian_linux:apache2-ssl-dev, p-cpe:/a:debian:debian_linux:apache2-suexec-custom, p-cpe:/a:debian:debian_linux:apache2-suexec-pristine, p-cpe:/a:debian:debian_linux:apache2-utils, cpe:/o:debian:debian_linux:9.0

Required KB Items: Host/local_checks_enabled, Host/Debian/release, Host/Debian/dpkg-l

Exploit Ease: No known exploits are available

Patch Publication Date: 7/9/2021

Vulnerability Publication Date: 4/1/2020

Reference Information

CVE: CVE-2020-1927, CVE-2020-1934, CVE-2020-35452, CVE-2021-26690, CVE-2021-26691, CVE-2021-30641, CVE-2021-31618

IAVA: 2020-A-0129-S, 2020-A-0326, 2021-A-0259-S