Vulnerability · Published Dec 9, 2020 · Assigned by mozilla
CVE-2020-26956
Medium 6.1
In plain English
A medium-severity security flaw in Firefox from Mozilla. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.2% (higher than 69% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS NVD)6.1Medium
Exploit odds (30 days)1.2%top 30.9% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | firefox | 83.0-r0 | ALPINE-CVE-2020-26956 |
| Alpine:v3.21 | firefox | 83.0-r0 | ALPINE-CVE-2020-26956 |
| Alpine:v3.22 | firefox | 83.0-r0 | ALPINE-CVE-2020-26956 |
| Alpine:v3.23 | firefox | 83.0-r0 | ALPINE-CVE-2020-26956 |
| Alpine:v3.20 | firefox-esr | 78.5.0-r0 | ALPINE-CVE-2020-26956 |
| Alpine:v3.21 | firefox-esr | 78.5.0-r0 | ALPINE-CVE-2020-26956 |
| Alpine:v3.22 | firefox-esr | 78.5.0-r0 | ALPINE-CVE-2020-26956 |
| Alpine:v3.23 | firefox-esr | 78.5.0-r0 | ALPINE-CVE-2020-26956 |
| Alpine:v3.21 | librewolf | 83.0-r0 | ALPINE-CVE-2020-26956 |
| Alpine:v3.22 | librewolf | 83.0-r0 | ALPINE-CVE-2020-26956 |
| Alpine:v3.23 | librewolf | 83.0-r0 | ALPINE-CVE-2020-26956 |
| Alpine:v3.24 | librewolf | 83.0-r0 | ALPINE-CVE-2020-26956 |
| Alpine:v3.20 | thunderbird | 78.5.1-r0 | ALPINE-CVE-2020-26956 |
| Alpine:v3.21 | thunderbird | 78.5.1-r0 | ALPINE-CVE-2020-26956 |
| Alpine:v3.22 | thunderbird | 78.5.1-r0 | ALPINE-CVE-2020-26956 |
| Alpine:v3.23 | thunderbird | 78.5.1-r0 | ALPINE-CVE-2020-26956 |
| Debian:12 | firefox-esr | 78.5.0esr-1 | DEBIAN-CVE-2020-26956 |
| Debian:13 | firefox-esr | 78.5.0esr-1 | DEBIAN-CVE-2020-26956 |
| Debian:14 | firefox-esr | 78.5.0esr-1 | DEBIAN-CVE-2020-26956 |
| Debian:12 | thunderbird | 1:78.5.0-1 | DEBIAN-CVE-2020-26956 |
| Debian:13 | thunderbird | 1:78.5.0-1 | DEBIAN-CVE-2020-26956 |
| Debian:14 | thunderbird | 1:78.5.0-1 | DEBIAN-CVE-2020-26956 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | < 83 |
| Mozilla | Firefox ESR | < 78.5 |
| Mozilla | Thunderbird | < 78.5 |
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1666300 x_refsource_MISC
- https://www.mozilla.org/security/advisories/mfsa2020-50/ x_refsource_CONFIRM
- https://www.mozilla.org/security/advisories/mfsa2020-52/ x_refsource_CONFIRM
- https://www.mozilla.org/security/advisories/mfsa2020-51/ x_refsource_CONFIRM