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
02 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
03 Exploitation and scoring
- Exploitation
- Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.
- SSVC decision
- Not assessed by CISA
- EPSS probability
- 42.32% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 98.5% of scored records. A rank, not a probability.
- NVD base score
- 8.8 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- NVD analysis status
- Modified. NVD last modified this record on 2026-06-17.
- Red Hat severity
- Critical. Red Hat's rating for its own products, not a CVSS rating.
Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.
04 Metadata
- Published
- 2020-12-09 00:19Z5 YR AGO
- Last updated
- 2024-08-04 16:03Z2 YR AGO
- Reserved
- 2020-10-12
- Assigning CNA
- mozilla
- Record state
- PUBLISHED
- Severity
- Not rated by the issuing CNA
- CNA CVSS vector
- Not published by the issuing CNA
- Weaknesses
- CWE-416Use After FreeVariant
- Data version
- 5.1
- Document digest
- 82b505480b9b1937d8f4addacf5cafafca36d74902be01eb62c9f85477cf7f03
05 Affected products
06 References
- bugzilla.mozilla.orghttps://bugzilla.mozilla.org/show_bug.cgi?id=1675905
- www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2020-49/
- packetstormsecurity.comhttp://packetstormsecurity.com/files/166175/Firefox-MCallGetProperty-Write-Side-Effects-Use-After-Free.html
07 Fixed in
Arch Linux
- firefox Fixed in 82.0.3-1
Source: Arch Linux Security Tracker, the Arch Linux security team. Reformatted by exploit.cc.
Debian 12
- firefox-esr Fixed in 78.4.1esr-1
- thunderbird Fixed in 1:78.4.2-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 13
- firefox-esr Fixed in 78.4.1esr-1
- thunderbird Fixed in 1:78.4.2-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 14
- firefox-esr Fixed in 78.4.1esr-1
- thunderbird Fixed in 1:78.4.2-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 16.04 LTS
- firefox Fixed in 82.0.3+build1-0ubuntu0.16.04.1
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 18.04 LTS
- firefox Fixed in 82.0.3+build1-0ubuntu0.18.04.1
- mozjs38 No fix yet
- mozjs52 No fix yet
- thunderbird Fixed in 1:78.8.1+build1-0ubuntu0.18.04.1
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 20.04 LTS
- firefox Fixed in 82.0.3+build1-0ubuntu0.20.04.1
- mozjs52 No fix yet
- mozjs68 No fix yet
- thunderbird Fixed in 1:78.7.1+build1-0ubuntu0.20.04.1
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.