Firefox fixes flaw similar to Chrome zero

Mozilla Firefox and Firefox ESR contain a use-after-free (CWE-416) in the browser's animation timelines component, which CISA describes as allowing code execution in the content process. The flaw is reachable through malicious web content: a crafted page can manipulate animation timelines so that an in-use object is freed, producing exploitable memory corruption. A successful attacker gains code execution in the content process, the sandboxed process that renders web pages, on the machine of the user who loaded the content. All users of Firefox and Firefox ESR are affected by the flaw itself. It is being actively exploited: the vulnerability was added to CISA's Known Exploited Vulnerabilities catalog on 2024-10-15 with known ransomware use, and EPSS assigns it a 23.2% probability of exploitation in the next 30 days (98th percentile).

Do: Apply Mozilla's patched Firefox/Firefox ESR release immediately and verify the running version via the browser's About Firefox dialog, since many installs only pick up auto-updates after a restart (per CISA's required action: apply mitigations per vendor instructions or discontinue use). Given the known ransomware use, prioritize enterprise ESR rollout and check for managed-update failures, auto-update-disabled installs, or unmanaged Firefox copies on user machines. Note that no public proof-of-concept is known, but KEV listing confirms exploitation, so patching should not wait for PoC availability.

CVE-2025-2783 is a high-severity sandbox escape in Google Chrome on Windows, caused by an incorrect handle being provided in unspecified circumstances in Mojo, Chrome's inter-process communication layer. It is triggered remotely through a malicious file and requires user interaction; an attacker who has code running inside Chrome's sandboxed renderer can abuse the handle flaw to break out of the Windows sandbox and gain broader access to the host (CVSS scope change with high impact to confidentiality, integrity, and availability). All Google Chrome versions on Windows prior to 134.0.6998.177 are affected, per the vendor fix referenced by CISA. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2025-03-27, and related reporting links it to active exploitation in the ForumTroll APT's phishing campaign against Russian scholars using fake eLibrary emails; ransomware use is unknown. No public proof-of-concept is known, and EPSS assigns a 9.2% probability of exploitation within 30 days (95th percentile).

Do: Update Google Chrome on Windows to 134.0.6998.177 or later immediately and verify deployed browser versions across endpoints; the flaw is in the CISA KEV catalog, so federal agencies must apply vendor mitigations per BOD 22-01 timelines. Because exploitation is tied to malicious files delivered via phishing (e.g., the ForumTroll fake-eLibrary campaign), prioritize patching for users who open untrusted attachments and links, and hunt for associated phishing emails.

Following the recent Chrome sandbox escape (CVE-2025-2783), various Firefox developers identified a similar pattern in our IPC code. A compromised child process could cause the parent process to return an unintentionally powerful handle, leading to a sandbox escape. The original vulnerability was being exploited in the wild. *This only affects Firefox on Windows. Other operating systems are unaffected.*. This vulnerability was fixed in Firefox 136.0.4, Firefox ESR 128.8.1, and Firefox ESR 115.21.1.