CVE-2020-26951: mozilla firefox Cross-site Scripting
Vulnerability summary
CVE-2020-26951 is a medium (CVSS 6.1) Cross-site Scripting vulnerability in mozilla firefox. EPSS estimates a 1.05% chance of exploitation in the next 30 days, higher than 63.6% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 33 · Related 15Timeline
- 09-12-2020PublishedVulnerability first disclosed.
- 04-08-2024Last modifiedVulnerability information updated.
Description
A parsing and event loading mismatch in Firefox's SVG code could have allowed load events to fire, even after sanitization. An attacker already capable of exploiting an XSS vulnerability in privileged internal pages could have used this attack to bypass our built-in sanitizer. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.
CVSS metrics
4 scores · 3 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated6.1MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- OSV · DebianEcosystem advisory · calculated6.1MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS trend
Probability
1.05%
Chance of exploitation in the next 30 days
Percentile
64%
Versus all other CVEs
30-day change
0.00 pp
From 1.05% on 18-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Ubuntu5 products
- firefox< 83.0+build2-0ubuntu0.16.04.3 | < 83.0+build2-0ubuntu0.18.04.2 | < 83.0+build2-0ubuntu0.20.04.1
- mozjs38All versions (No fix recorded)
- mozjs52All versions (No fix recorded)
- mozjs68All versions (No fix recorded)
- thunderbird< 1:78.8.1+build1-0ubuntu0.18.04.1 | < 1:78.7.1+build1-0ubuntu0.20.04.1
Mozilla3 products
- firefox< 83 | < 83.0
- firefox_esr< 78.5
- thunderbird< 78.5
Debian2 products
- firefox-esr< 78.5.0esr-1
- thunderbird< 1:78.5.0-1
3 vendors · 10 products
References
12 links- bugzilla.mozilla.org/show_bug.cgi?id=1667113X Refsource MISCIssue TrackingPermissions RequiredVendor Advisory
