Mozilla Firefox/Thunderbird SVG Event cross site scripting

CVSS Meta Temp Score
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CTI Interest Score
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5.1$0-$5k0.00

Summaryinfo

A vulnerability was found in Mozilla Firefox and Thunderbird. It has been declared as problematic. This affects an unknown part of the component SVG Event Handler. Such manipulation leads to cross site scripting. This vulnerability is traded as CVE-2020-26956. The attack may be launched remotely. There is no exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Mozilla Firefox and Thunderbird (Web Browser) (version now known) and classified as problematic. Affected by this issue is some unknown processing of the component SVG Event Handler. The manipulation with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Impacted is integrity.

The weakness was shared 12/09/2020 as mfsa2020-50. The advisory is available at mozilla.org. This vulnerability is handled as CVE-2020-26956. Successful exploitation requires user interaction by the victim. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1059.007 by the MITRE ATT&CK project.

The vulnerability scanner Nessus provides a plugin with the ID 249880 (Linux Distros Unpatched Vulnerability : CVE-2020-26956), which helps to determine the existence of the flaw in a target environment.

Upgrading eliminates this vulnerability. The upgrade is hosted for download at mozilla.org.

The vulnerability is also documented in the databases at Tenable (249880) and CERT Bund (WID-SEC-2026-0337). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

  • Open Source CentOS
  • Debian Linux
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • Gentoo Linux
  • Open Source Arch Linux
  • Mozilla Firefox
  • Mozilla Firefox ESR
  • Mozilla Thunderbird

Productinfo

Type

Vendor

Name

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.2
VulDB Meta Temp Score: 5.1

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 6.1
NVD Vector: 🔍

CVSSv2info

AVACAuCIA
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 249880
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2020-26956

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: mozilla.org

Timelineinfo

10/12/2020 🔍
12/09/2020 +58 days 🔍
12/09/2020 +0 days 🔍
02/09/2026 +1888 days 🔍

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: mfsa2020-50
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2020-26956 (🔍)
GCVE (CVE): GCVE-0-2020-26956
GCVE (VulDB): GCVE-100-165794
CERT Bund: WID-SEC-2026-0337 - Mozilla Firefox und Thunderbird: Mehrere Schwachstellen

Entryinfo

Created: 12/09/2020 10:44
Updated: 02/09/2026 10:28
Changes: 12/09/2020 10:44 (41), 12/14/2020 08:21 (5), 12/14/2020 08:27 (18), 08/18/2025 04:46 (17), 02/09/2026 10:28 (7)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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