CVE-2020-6819
Under certain conditions, when running the nsDocShell destructor, a race condition can cause a use-after-free. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability
02 Description
Under certain conditions, when running the nsDocShell destructor, a race condition can cause a use-after-free. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability
03 Exploitation and scoring
- Exploitation
- Exploited in the wild. Listed in the CISA Known Exploited Vulnerabilities catalog on 2021-11-03. Federal remediation due 2022-05-03.
- SSVC decision
- ExploitationactiveCISA reports credible evidence of active exploitation.
- AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
- Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.
- EPSS probability
- 3.03% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 87.2% of scored records. A rank, not a probability.
- NVD base score
- 8.1 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- NVD analysis status
- Analyzed. 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
- 2020-04-24 15:56Z6 YR AGO
- Last updated
- 2025-10-21 23:35Z1 YR AGO
- Reserved
- 2020-01-10
- Assigning CNA
- mozilla
- Record state
- PUBLISHED
- Severity
- High (CVSS 8.1)
- CNA CVSS vector
- CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weaknesses
- Data version
- 5.1
- Document digest
- 09d340da559f7ed700f43331249993c6ede638f22e5e042440cf5eeff6f10fe2
05 Affected products
06 References
- www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2020-14/
- www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2020-11/
- bugzilla.mozilla.orghttps://bugzilla.mozilla.org/show_bug.cgi?id=1620818
- usn.ubuntu.comUSN-4335-1https://usn.ubuntu.com/4335-1/
- www.cisa.govhttps://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-6819
07 Fixed in
Arch Linux
- firefox Fixed in 74.0.1-1
- thunderbird Fixed in 68.7.0-1
Source: Arch Linux Security Tracker, the Arch Linux security team. Reformatted by exploit.cc.
Debian 12
- firefox-esr Fixed in 68.6.1esr-1
- thunderbird Fixed in 1:68.7.0-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 13
- firefox-esr Fixed in 68.6.1esr-1
- thunderbird Fixed in 1:68.7.0-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 14
- firefox-esr Fixed in 68.6.1esr-1
- thunderbird Fixed in 1:68.7.0-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 16.04 LTS
- firefox Fixed in 74.0.1+build1-0ubuntu0.16.04.1
- thunderbird Fixed in 1:68.7.0+build1-0ubuntu0.16.04.2
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 74.0.1+build1-0ubuntu0.18.04.1
- thunderbird Fixed in 1:68.7.0+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 75.0+build3-0ubuntu1
- thunderbird Fixed in 1:68.7.0+build1-0ubuntu1
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.