The lifecycle of IPC Actors allows managed actors to outlive their manager actors; and the former must ensure that they are not attempting…

published 2021-01-07 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-19496

cvss: 9.8; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.3%; EPSS 1.3% chance of exploitation in 30 days, percentile 70%
public exploits: 0; none known

The lifecycle of IPC Actors allows managed actors to outlive their manager actors; and the former must ensure that they are not attempting to use a dead actor they have a reference to. Such a check was omitted in WebGL, resulting in a use-after-free and a potentially exploitable crash. This vulnerability affects Firefox < 84.

Patch / fix

fixed in 1 distros 4

Mozilla Firefox 84

ubuntu opensuse alpine arch linux

firefox Ubuntu 16.04 LTS 84.0+build3-0ubuntu0.16.04.1
firefox Ubuntu 18.04 LTS 84.0+build3-0ubuntu0.18.04.1
firefox Ubuntu 20.04 LTS 84.0+build3-0ubuntu0.20.04.1

ubuntu advisories UBUNTU-CVE-2020-26972

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

firefox-esr openSUSE Tumbleweed 128.5.1-1.1
MozillaFirefox openSUSE Tumbleweed 92.0-1.2

opensuse advisories openSUSE-SU-2024:14572-1 openSUSE-SU-2024:10600-1

firefox Alpine 3.23, Alpine 3.22, Alpine 3.21 +9 more 84.0.1-r0
librewolf Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 84.0.1-r0

alpine advisories ALPINE-CVE-2020-26972

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

firefox Arch Linux 84.0-1

arch linux advisories AVG-1362

Exploit prediction

1.31% chance of exploitation in the next 30 days, higher than 70% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	7.5	AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

Mozilla Firefox

Classification

Weakness

CWE-416 Use After Free

References

mozilla.org /security/advisories/mfsa2020-54/
vendor-advisory
bugzilla.mozilla.org /show_bug.cgi?id=1671382
permissions-required

Sources

CVE List CVE-2020-26972
NVD CVE-2020-26972

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary