CVE-2020-26950
In certain circumstances, the MCallGetProperty opcode can be emitted with unmet assumptions resulting in an exploitable use-after-free condition.
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 42.3%, higher than 99% of all known CVEs. Patch or mitigate before the next change window.
Description
In certain circumstances, the MCallGetProperty opcode can be emitted with unmet assumptions resulting in an exploitable use-after-free condition. This vulnerability affects Firefox < 82.0.3, Firefox ESR < 78.4.1, and Thunderbird < 78.4.2.
- 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
- 42.33% probability · 99th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-416
- Affected
- mozilla/firefox · mozilla/firefox esr · mozilla/thunderbird
- Source
- security@mozilla.org
EPSS 42.3% since 26 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- http://packetstormsecurity.com/files/166175/Firefox-MCallGetProperty-Write-Side-Effects-Use-After-Free.htmlExploit, Third Party Advisory, VDB Entry
- https://bugzilla.mozilla.org/show_bug.cgi?id=1675905Exploit, Issue Tracking, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-49/Vendor Advisory
- http://packetstormsecurity.com/files/166175/Firefox-MCallGetProperty-Write-Side-Effects-Use-After-Free.htmlExploit, Third Party Advisory, VDB Entry
- https://bugzilla.mozilla.org/show_bug.cgi?id=1675905Exploit, Issue Tracking, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-49/Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.