Mozilla Firefox Security Advisory (MFSA2021-28) - Linux

# SPDX-FileCopyrightText: 2021 Greenbone AG
# Some text descriptions might be excerpted from (a) referenced
# source(s), and are Copyright (C) by the respective right holder(s).
#
# SPDX-License-Identifier: GPL-2.0-only

CPE = "cpe:/a:mozilla:firefox";

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.2.1.2021.28");
  script_version("2026-07-02T06:53:57+0000");
  script_tag(name:"last_modification", value:"2026-07-02 06:53:57 +0000 (Thu, 02 Jul 2026)");
  script_tag(name:"creation_date", value:"2021-11-08 15:21:25 +0000 (Mon, 08 Nov 2021)");
  script_tag(name:"cvss_base", value:"6.8");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:M/Au:N/C:P/I:P/A:P");
  script_tag(name:"severity_vector", value:"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H");
  script_tag(name:"severity_origin", value:"NVD");
  script_tag(name:"severity_date", value:"2021-06-17 20:25:14 +0000 (Thu, 17 Jun 2021)");

  script_cve_id("CVE-2021-29970", "CVE-2021-29972", "CVE-2021-29974", "CVE-2021-29975", "CVE-2021-29976", "CVE-2021-29977", "CVE-2021-30547");

  script_name("Mozilla Firefox Security Advisory (MFSA2021-28) - Linux");

  script_category(ACT_GATHER_INFO);

  script_copyright("Copyright (C) 2021 Greenbone AG");
  script_family("General");
  script_dependencies("gb_firefox_detect_lin.nasl");
  script_mandatory_keys("mozilla/firefox/linux/detected");

  script_xref(name:"Advisory-ID", value:"MFSA2021-28");
  script_xref(name:"URL", value:"https://www.mozilla.org/en-US/security/advisories/mfsa2021-28/");
  script_xref(name:"URL", value:"https://bugzilla.mozilla.org/buglist.cgi?bug_id=1665836%2C1686138%2C1704316%2C1706314%2C1709931%2C1712084%2C1712357%2C1714066");
  script_xref(name:"URL", value:"https://bugzilla.mozilla.org/buglist.cgi?bug_id=1696816");
  script_xref(name:"URL", value:"https://bugzilla.mozilla.org/buglist.cgi?bug_id=1700895%2C1703334%2C1706910%2C1711576%2C1714391");
  script_xref(name:"URL", value:"https://bugzilla.mozilla.org/buglist.cgi?bug_id=1704843");
  script_xref(name:"URL", value:"https://bugzilla.mozilla.org/buglist.cgi?bug_id=1709976");
  script_xref(name:"URL", value:"https://bugzilla.mozilla.org/buglist.cgi?bug_id=1713259");
  script_xref(name:"URL", value:"https://bugzilla.mozilla.org/buglist.cgi?bug_id=1715766");

  script_tag(name:"summary", value:"The remote host is missing an update for Mozilla Firefox, announced via the advisory MFSA2021-28.");

  script_tag(name:"vuldetect", value:"Checks if a vulnerable package version is present on the target host.");

  script_tag(name:"insight", value:"CVE-2021-29970: Use-after-free in accessibility features of a document

A malicious webpage could have triggered a use-after-free, memory corruption, and a potentially exploitable crash. *This bug only affected Firefox when accessibility was enabled.*

CVE-2021-30547: Out of bounds write in ANGLE

An out of bounds write in ANGLE could have allowed an attacker to corrupt memory leading to a potentially exploitable crash.

CVE-2021-29972: Use of out-of-date library included use-after-free vulnerability

A user-after-free vulnerability was found via testing, and traced to an out-of-date Cairo library. Updating the library resolved the issue, and may have remediated other, unknown security vulnerabilities as well.

CVE-2021-29974: HSTS errors could be overridden when network partitioning was enabled

When network partitioning was enabled, e.g. as a result of Enhanced Tracking Protection settings, a TLS error page would allow the user to override an error on a domain which had specified HTTP Strict Transport Security (which implies that the error should not be override-able.) This issue did not affect the network connections, and they were correctly upgraded to HTTPS automatically.

CVE-2021-29975: Text message could be overlaid on top of another website

Through a series of DOM manipulations, a message, over which the attacker had control of the text but not HTML or formatting, could be overlaid on top of another domain (with the new domain correctly shown in the address bar) resulting in possible user confusion.

CVE-2021-29976: Memory safety bugs fixed in Firefox 90 and Firefox ESR 78.12

Mozilla developers Emil Ghitta, Tyson Smith, Valentin Gosu, Olli Pettay, and Randell Jesup reported memory safety bugs present in Firefox 89 and Firefox ESR 78.11. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code.

CVE-2021-29977: Memory safety bugs fixed in Firefox 90

Mozilla developers Andrew McCreight, Tyson Smith, Christian Holler, and Gabriele Svelto reported memory safety bugs present in Firefox 89. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code.");

  script_tag(name:"affected", value:"Mozilla Firefox versions prior to 90.");

  script_tag(name:"solution", value:"The vendor has released an update. Please see the reference(s) for more information.");

  script_tag(name:"solution_type", value:"VendorFix");
  script_tag(name:"qod_type", value:"executable_version_unreliable");

  exit(0);
}

include("host_details.inc");
include("version_func.inc");

if (!infos = get_app_version_and_location(cpe: CPE, exit_no_version: TRUE))
  exit(0);

version = infos["version"];
location = infos["location"];

if (version_is_less(version: version, test_version: "90")) {
  report = report_fixed_ver(installed_version: version, fixed_version: "90", install_path: location);
  security_message(port: 0, data: report);
  exit(0);
}

exit(99);