CVE-2026-3846 | Same-origin policy bypass in the CSS Parsing and Computation component

Same-origin policy bypass in the CSS Parsing and Computation component. This vulnerability was fixed in Firefox 148.0.2.

Published: 2026-03-10 Last update: 2026-04-13 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-3846 is rated Low Risk (26.9/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.01%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-3846

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-11 — 0.01% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-3846

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-3846

OS Trackers for CVE-2026-3846

vendor priority summary link
alpine — CVE-2026-3846: 1 source package rows (firefox); 128 state rows across 2 repos (3.23-community, edge-community); fixed 0, open 128. https://security.alpinelinux.org/vuln/CVE-2026-3846
debian not yet assigned CVE-2026-3846 not yet assigned priority: Debian including 1 source packages (firefox), 1 status rows across 1 suites (sid): resolved 1. https://security-tracker.debian.org/tracker/CVE-2026-3846
suse high CVE-2026-3846 severity important: SUSE including 14 source package names (MozillaFirefox, MozillaFirefox-148.0.2-1.1, …), 88 product×package rows across 24 product lines (SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS, SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS, … (24 product lines)): Known Not Affected 83, Fixed 5. https://www.suse.com/security/cve/CVE-2026-3846/
ubuntu medium CVE-2026-3846 medium priority: Ubuntu including 9 source packages (firefox, mozjs102, …), 40 status rows across 6 suites (bionic, focal, jammy, noble, questing, upstream): DNE 16, needs-triage 10, ignored 8, not-affected 5, needed 1. https://ubuntu.com/security/CVE-2026-3846

Affected software / configurations for CVE-2026-3846

Vendor Product Version Raw CPE
mozilla firefox < 148.0.2 cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*

References for CVE-2026-3846

cvelogic Threat Intelligence