CVE-2020-26951

Mozilla: Parsing mismatches could confuse and bypass security sanitizer for chrome privileged code

Severity Score

6.1

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

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.

Un desajuste en el análisis y la carga de eventos en el código SVG de Firefox podría haber permitido a unos eventos de carga dispararse, incluso después del saneamiento. Un atacante ya capaz de explotar una vulnerabilidad de tipo XSS en páginas internas privilegiadas podría haber usado este ataque para omitir nuestro sanitizador incorporado. Esta vulnerabilidad afecta a Firefox versiones anteriores a 83, Firefox ESR versiones anteriores a 78.5, y Thunderbird versiones anteriores a 78.5

Multiple security issues were discovered in Thunderbird. If a user were tricked in to opening a specially crafted website in a browsing context, an attacker could potentially exploit these to cause a denial of service, obtain sensitive information across origins, bypass security restrictions, conduct phishing attacks, conduct cross-site scripting attacks, bypass Content Security Policy restrictions, conduct DNS rebinding attacks, or execute arbitrary code.

*Credits: N/A

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Attack Vector

Network

Attack Complexity

Medium

Authentication

None

Confidentiality

None

Integrity

Partial

Availability

None

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2020-10-12 CVE Reserved
2020-11-26 CVE Published
2024-08-04 CVE Updated
2025-03-30 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-354: Improper Validation of Integrity Check Value

CAPEC

References (5)

URL	Tag	Source

URL	Date	SRC

URL	Date	SRC

URL	Date	SRC
https://www.mozilla.org/security/advisories/mfsa2020-50	2020-12-09
https://www.mozilla.org/security/advisories/mfsa2020-51	2020-12-09
https://www.mozilla.org/security/advisories/mfsa2020-52	2020-12-09
https://access.redhat.com/security/cve/CVE-2020-26951	2020-12-01
https://bugzilla.redhat.com/show_bug.cgi?id=1898731	2020-12-01

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Mozilla Search vendor "Mozilla"		Firefox Search vendor "Mozilla" for product "Firefox"				< 83.0 Search vendor "Mozilla" for product "Firefox" and version " < 83.0"		-		Affected
Mozilla Search vendor "Mozilla"		Firefox Esr Search vendor "Mozilla" for product "Firefox Esr"				< 78.5 Search vendor "Mozilla" for product "Firefox Esr" and version " < 78.5"		-		Affected
Mozilla Search vendor "Mozilla"		Thunderbird Search vendor "Mozilla" for product "Thunderbird"				< 78.5 Search vendor "Mozilla" for product "Thunderbird" and version " < 78.5"		-		Affected