CVE-2020-26970
Depending on processor architecture and stack layout, this leads to stack corruption that may be exploitable.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.25%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
When reading SMTP server status codes, Thunderbird writes an integer value to a position on the stack that is intended to contain just one byte. Depending on processor architecture and stack layout, this leads to stack corruption that may be exploitable. This vulnerability affects Thunderbird < 78.5.1.
- CVSS 3.1
- 8.8 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- EPSS
- 1.25% probability · 69th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-787
- Affected
- mozilla/thunderbird
- Source
- security@mozilla.org
EPSS 1.2% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1677338Issue Tracking, Permissions Required, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-53/Vendor Advisory
- https://bugzilla.mozilla.org/show_bug.cgi?id=1677338Issue Tracking, Permissions Required, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-53/Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.