Back
CVE-2020-6806By carefully crafting promise resolutions, it was possible to cause an out-of-bounds read off the end of an array resized during script…
- 8.8HighCVSS base score
- 2.6%Exploitation in 30 daysEPSS · top 14% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
By carefully crafting promise resolutions, it was possible to cause an out-of-bounds read off the end of an array resized during script execution. This could have led to memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 68.6, Firefox < 74, Firefox < ESR68.6, and Firefox ESR < 68.6.
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 | High8.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 2.6% · top 14% of all CVEs (13 Nov 2026)
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.8.
Affected products
- affected unspecified – < 68.6
- affected unspecified – < 74
- affected unspecified – < ESR68.6
- affected unspecified – < 68.6
References
References7
- https://www.mozilla.org/security/advisories/mfsa2020-08/ (opens in a new tab)x_refsource_MISCx_transferred
- https://www.mozilla.org/security/advisories/mfsa2020-10/ (opens in a new tab)x_refsource_MISCx_transferred
- https://www.mozilla.org/security/advisories/mfsa2020-09/ (opens in a new tab)x_refsource_MISCx_transferred
- https://bugzilla.mozilla.org/show_bug.cgi?id=1612308 (opens in a new tab)x_refsource_MISCx_transferred
- USN-4328-1 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
- USN-4335-1 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
- http://packetstormsecurity.com/files/157524/Firefox-js-ReadableStreamCloseInternal-Out-Of-Bounds-Access.html (opens in a new tab)x_refsource_MISCx_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)
- EUVD EUVD-2020-27952 (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://cveledger.app/cve/CVE-2020-6806)Record last updated .