CVE-2020-26956: XSS
First published: Tue Nov 17 2020(Updated: )
In some cases, removing HTML elements during sanitization would keep existing SVG event handlers and therefore lead to XSS.
Credit: security@mozilla.org
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Mozilla Firefox ESR | <78.5 | 78.5 |
| <83 | 83 | |
| <78.5 | 78.5 | |
| <78.5 | 78.5 | |
| Mozilla Firefox | <83.0 | |
| Mozilla Firefox ESR | <78.5 | |
| Mozilla Thunderbird | <78.5 |
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Reference Links
- https://bugzilla.mozilla.org/show_bug.cgi?id=1666300
- https://www.mozilla.org/en-US/security/advisories/mfsa2020-51/
- https://www.mozilla.org/en-US/security/advisories/mfsa2020-50/
- https://www.mozilla.org/en-US/security/advisories/mfsa2020-52/
- https://www.mozilla.org/security/advisories/mfsa2020-50/
- https://www.mozilla.org/security/advisories/mfsa2020-51/
- https://www.mozilla.org/security/advisories/mfsa2020-52/
Peer vulnerabilities
(Found alongside the following vulnerabilities)
Frequently Asked Questions
What is the vulnerability ID for this issue?
The vulnerability ID for this issue is CVE-2020-26956.
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.
What is the severity of CVE-2020-26956?
The severity of CVE-2020-26956 is medium (severity value: 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.
How can I fix CVE-2020-26956?
To fix CVE-2020-26956, update to the appropriate version of Mozilla Firefox ESR or Mozilla Thunderbird.
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