Critical (9.8) in mozilla firefox. EPSS 0.4% chance of exploitation in the next 30 days.
The `fetch()` API and navigation incorrectly shared the same cache, as the cache key did not include the optional headers `fetch()` may contain. Under the correct circumstances, an attacker may have been able to poison the local browser cache by priming it with a `fetch()` response controlled by the additional headers. Upon navigation to the same URL, the user would see the cached response instead of the expected response. This vulnerability affects Firefox < 123.
Severity
CVSS 3.1
9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
0.4% chance of exploitation in the next 30 days; higher than 32% of CVEs (scores of 2026-10-31)