Use After Free in Mozilla Firefox
CVE-2020-26950
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.
Vulnerability class: Use-After-Free
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.423 (98.7th percentile), scored .
Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 99th percentile — 98.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.423 · newest: 0.423 · change: 0.000
Affected products
- Mozilla Firefox — versions < 82.0.3
- Mozilla Firefox Esr — versions < 78.4.1
- Mozilla Firefox Esr
- Mozilla Thunderbird — versions < 78.4.2
Weakness classification (CWE)
Public proof-of-concept exploits
References
- bugzilla.mozilla.org/show_bug.cgi (Exploit, Issue Tracking, Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2020-49/ (Vendor Advisory)
- packetstormsecurity.com/files/166175/Firefox-MCallGetProperty-Write-Side-Effect… (Exploit, VDB Entry, Third Party Advisory)
Frequently asked questions
- What is CVE-2020-26950?
- CVE-2020-26950 is a high-severity vulnerability in Mozilla Firefox, classified under Use After Free. CVSS score: 8.8/10. Published 2020-12-09.
- How severe is CVE-2020-26950?
- High severity. CVSS v3 base score is 8.8 out of 10.
- Is CVE-2020-26950 known to be exploited?
- 4 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.