CVE-2020-26956: XSS
Published Nov 17, 2020
·Updated
In some cases, removing HTML elements during sanitization would keep existing SVG event handlers and therefore lead to XSS.
Affected Software
6 affected componentsFixes available
Mozilla Thunderbird<78.5
78.5
Mozilla Firefox<83.0
Mozilla Firefox ESR<78.5
Mozilla Thunderbird<78.5
Mozilla Firefox<83
83
Mozilla Firefox ESR<78.5
78.5
Event History
Nov 17, 2020
CVE Published
12:00 AM
Dec 9, 2020
CVE Published
via MITRE·12:21 AM
Data Sourced
via MITRE·12:21 AM
DescriptionWeakness
Parent advisories
This vulnerability appears in the following advisories.
Peer vulnerabilities
Found alongside the following vulnerabilities.
Frequently Asked Questions
1
What is the vulnerability ID for this issue?
The vulnerability ID for this issue is CVE-2020-26956.
2
What is the affected software?
The affected software includes Mozilla Firefox ESR version up to 78.5, Mozilla Firefox version up to 83, and Mozilla Thunderbird version up to 78.5.
3
What is the severity of CVE-2020-26956?
The severity of CVE-2020-26956 is medium (severity value: 4).
4
How does CVE-2020-26956 affect the software?
CVE-2020-26956 can lead to XSS (cross-site scripting) by allowing existing SVG event handlers to remain after removing HTML elements during sanitization.
5
How can I fix CVE-2020-26956?
To fix CVE-2020-26956, update to the appropriate version of Mozilla Firefox ESR or Mozilla Thunderbird.