CVE-2021-23961
Further techniques that built on the slipstream research combined with a malicious webpage could have exposed both an internal network's hosts as well as services running on the user's local machine.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.48%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
Further techniques that built on the slipstream research combined with a malicious webpage could have exposed both an internal network's hosts as well as services running on the user's local machine. This vulnerability affects Firefox < 85.
- CVSS 3.1
- 7.4 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N
- EPSS
- 1.48% probability · 74th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Affected
- mozilla/firefox · debian/debian linux
- Source
- security@mozilla.org
EPSS 1.5% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1677940Issue Tracking, Permissions Required, Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2021/04/msg00019.htmlMailing List, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2021/04/msg00020.htmlMailing List, Third Party Advisory
- https://security.gentoo.org/glsa/202104-09Third Party Advisory
- https://security.gentoo.org/glsa/202104-10Third Party Advisory
- https://www.debian.org/security/2021/dsa-4895Third Party Advisory
- https://www.debian.org/security/2021/dsa-4897Third Party Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-03/Release Notes, Vendor Advisory
- https://bugzilla.mozilla.org/show_bug.cgi?id=1677940Issue Tracking, Permissions Required, Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2021/04/msg00019.htmlMailing List, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2021/04/msg00020.htmlMailing List, Third Party Advisory
- https://security.gentoo.org/glsa/202104-09Third Party Advisory
- https://security.gentoo.org/glsa/202104-10Third Party Advisory
- https://www.debian.org/security/2021/dsa-4895Third Party Advisory
- https://www.debian.org/security/2021/dsa-4897Third Party Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-03/Release Notes, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.