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CVE-2020-26976
When a HTTPS pages was embedded in a HTTP page, and there was a service worker registered for the former, the service worker could have…
Medium6.5EPSS 1.6%
- Published
- Updated
- Reserved
- Assigned by
- mozilla
Description
When a HTTPS pages was embedded in a HTTP page, and there was a service worker registered for the former, the service worker could have intercepted the request for the secure page despite the iframe not being a secure context due to the (insecure) framing. This vulnerability affects Firefox < 84.
Timeline
ID reserved
By mozilla
- 3 months later
· 3 months later
Published
- 4 years later
· 4 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | Medium6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N |
- EPSS (exploitation in 30 days)
- 1.6% · top 23% of all CVEs (7 Nov 2026)
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.5.
Weakness
- HTTPS pages could have been intercepted by a registered service worker when they should not have been
Affected products
References (7)
- https://www.mozilla.org/security/advisories/mfsa2020-54/ (opens in a new tab)x_refsource_MISCx_transferred
- https://bugzilla.mozilla.org/show_bug.cgi?id=1674343 (opens in a new tab)x_refsource_MISCx_transferred
- DSA-4840 (opens in a new tab)vendor-advisoryx_refsource_DEBIANx_transferred
- GLSA-202102-02 (opens in a new tab)vendor-advisoryx_refsource_GENTOOx_transferred
- DSA-4842 (opens in a new tab)vendor-advisoryx_refsource_DEBIANx_transferred
- [debian-lts-announce] 20210202 [SECURITY] [DLA 2541-1] thunderbird security update (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- [debian-lts-announce] 20210202 [SECURITY] [DLA 2539-1] firefox-esr security update (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2020-26976)Record last updated .