CVE-2020-26956
MEDIUMCVSS 6.1/10EPSS 1.21%
Last modified
CVE-2020-26956 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. In some cases, removing HTML elements during sanitization would keep existing SVG event handlers and therefore lead to XSS. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.. EPSS estimates a 1.21% chance of exploitation in the next 30 days.
Description
In some cases, removing HTML elements during sanitization would keep existing SVG event handlers and therefore lead to XSS. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | < 83.0 |
| Mozilla | Firefox Esr | < 78.5 |
| Mozilla | Thunderbird | < 78.5 |
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1666300Issue Tracking, Permissions Required, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-50/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-51/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-52/Vendor Advisory
- https://bugzilla.mozilla.org/show_bug.cgi?id=1666300Issue Tracking, Permissions Required, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-50/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-51/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-52/Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
What is CVE-2020-26956?
In some cases, removing HTML elements during sanitization would keep existing SVG event handlers and therefore lead to XSS. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.
How severe is CVE-2020-26956?
CVE-2020-26956 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 1.21% probability of exploitation in the next 30 days.
How do I fix CVE-2020-26956?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
Are you affected by CVE-2020-26956?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST