Vulnerability · Published Dec 9, 2020 · Assigned by mozilla
CVE-2020-26958
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 1.4% (higher than 72% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS NVD)6.1Medium
Exploit odds (30 days)1.4%top 28.1% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known
Official description
Firefox did not block execution of scripts with incorrect MIME types when the response was intercepted and cached through a ServiceWorker. This could lead to a cross-site script inclusion vulnerability, or a Content Security Policy bypass. 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-2020-26958 |
| Alpine:v3.21 | firefox | 83.0-r0 | ALPINE-CVE-2020-26958 |
| Alpine:v3.22 | firefox | 83.0-r0 | ALPINE-CVE-2020-26958 |
| Alpine:v3.23 | firefox | 83.0-r0 | ALPINE-CVE-2020-26958 |
| Alpine:v3.20 | firefox-esr | 78.5.0-r0 | ALPINE-CVE-2020-26958 |
| Alpine:v3.21 | firefox-esr | 78.5.0-r0 | ALPINE-CVE-2020-26958 |
| Alpine:v3.22 | firefox-esr | 78.5.0-r0 | ALPINE-CVE-2020-26958 |
| Alpine:v3.23 | firefox-esr | 78.5.0-r0 | ALPINE-CVE-2020-26958 |
| Alpine:v3.21 | librewolf | 83.0-r0 | ALPINE-CVE-2020-26958 |
| Alpine:v3.22 | librewolf | 83.0-r0 | ALPINE-CVE-2020-26958 |
| Alpine:v3.23 | librewolf | 83.0-r0 | ALPINE-CVE-2020-26958 |
| Alpine:v3.24 | librewolf | 83.0-r0 | ALPINE-CVE-2020-26958 |
| Alpine:v3.20 | thunderbird | 78.5.1-r0 | ALPINE-CVE-2020-26958 |
| Alpine:v3.21 | thunderbird | 78.5.1-r0 | ALPINE-CVE-2020-26958 |
| Alpine:v3.22 | thunderbird | 78.5.1-r0 | ALPINE-CVE-2020-26958 |
| Alpine:v3.23 | thunderbird | 78.5.1-r0 | ALPINE-CVE-2020-26958 |
| Debian:12 | firefox-esr | 78.5.0esr-1 | DEBIAN-CVE-2020-26958 |
| Debian:13 | firefox-esr | 78.5.0esr-1 | DEBIAN-CVE-2020-26958 |
| Debian:14 | firefox-esr | 78.5.0esr-1 | DEBIAN-CVE-2020-26958 |
| Debian:12 | thunderbird | 1:78.5.0-1 | DEBIAN-CVE-2020-26958 |
| Debian:13 | thunderbird | 1:78.5.0-1 | DEBIAN-CVE-2020-26958 |
| Debian:14 | thunderbird | 1:78.5.0-1 | DEBIAN-CVE-2020-26958 |
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=1669355 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