CVE-2021-23986 Server-side request forgery in Firefox
A malicious Firefox extension could bypass same-origin policy to read responses from local-network or IP-authenticated resources via crafted search engine favicons.
- 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-2021-23986?
CVE-2021-23986 is a medium-severity server-side request forgery vulnerability in Mozilla Firefox, published on 31 Mar 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
A malicious extension with the 'search' permission could have installed a new search engine whose favicon referenced a cross-origin URL. The response to this cross-origin request could have been read by the extension, allowing a same-origin policy bypass by the extension, which should not have cross-origin permissions. This cross-origin request was made without cookies, so the sensitive information disclosed by the violation was limited to local-network resources or resources that perform IP-based authentication. This vulnerability affects Firefox < 87.
Weakness: CWE-346
Which versions are affected by CVE-2021-23986?
It affects 1 product.
Products include Mozilla Firefox.
How do I fix CVE-2021-23986?
Upgrade to a fixed version.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2021-23986 being exploited?
There is no known exploitation of CVE-2021-23986 in the wild and no public exploit code.
Other vulnerabilities in Mozilla Firefox
Sources
Also known as GHSA-3w6j-gj2m-vh4c, UBUNTU-CVE-2021-23986.