CVE-2020-26974 Use after free in Firefox
A type confusion in Firefox's flex-basis handling leads to a heap use-after-free, allowing attackers to execute arbitrary code or cause a crash.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2020-26974?
CVE-2020-26974 is a high-severity use after free vulnerability in Mozilla Firefox, published on 7 Jan 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
When flex-basis was used on a table wrapper, a StyleGenericFlexBasis object could have been incorrectly cast to the wrong type. This resulted in a heap user-after-free, memory corruption, and a potentially exploitable crash. This vulnerability affects Firefox < 84, Thunderbird < 78.6, and Firefox ESR < 78.6.
Weakness: CWE-787
Which versions are affected by CVE-2020-26974?
It affects 3 products.
Products include Mozilla Firefox, Mozilla Firefox Esr, Mozilla Thunderbird.
How do I fix CVE-2020-26974?
Upgrade to a fixed version.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2020-26974 being exploited?
There is no known exploitation of CVE-2020-26974 in the wild and no public exploit code.
Other vulnerabilities in Mozilla Firefox
Sources
Also known as DEBIAN-CVE-2020-26974, GHSA-gr4h-9jxj-93vm, UBUNTU-CVE-2020-26974.