CVE Alert: CVE-2010-3765 – n/a – n/a

Risk verdict

Urgent: active exploitation state is flagged, with a near‑total impact potential if exploited remotely.

Why this matters

Highly severe memory‑corruption vulnerability enables remote code execution without user interaction, giving an attacker full control of the affected host. It targets widely deployed browser suites, so unpatched endpoints across desktops and print/clinic/field environments are at risk of rapid, widespread compromise.

Most likely attack path

Exploitation requires no user interaction and no privileges, delivered over a network. An attacker can trigger code execution by luring a vulnerable browser to a crafted page or content, leveraging memory corruption through NSCSSFrameConstructor interactions. Once on a system, attacker control is total, with high impact on confidentiality, integrity and availability.

Who is most exposed

Any organisation with unmanaged or out‑of‑date Firefox, Thunderbird or SeaMonkey installations, especially on Windows endpoints and laptops used for web‑dense work. Enterprises with slow patch cycles or BYOD fleets are particularly at risk.

Detection ideas

• Look for crashes or memory‑corruption events tied to JavaScript rendering paths in affected browsers.
• Alerts around unusual process spawn patterns from browser processes.
• Network indicators of exploit traffic or known exploit‑db signatures targeting these versions.
• Correlated anomalous outbound/inbound traffic from endpoints immediately after navigating to unfamiliar sites.
• Check for indicators referencing Belmoo‑era payloads or related opportunistic campaigns.

Mitigation and prioritisation

• Apply vendor patches or upgrade to the latest supported browser versions immediately.
• Enforce automatic updates for Firefox/Thunderbird/SeaMonkey where feasible; verify patch succeeded.
• For high‑risk environments, consider temporary mitigation such as disabling JavaScript by default for untrusted sites or enabling stricter content security policies.
• Deploy endpoint monitoring/EDR rules to detect abnormal browser activity and memory‑corruption indicators.
• Change management: rapid containment, test patch compatibility, roll out in phased waves, with executive visibility due to exploitation state. If KEV or EPSS data later indicates high likelihood, elevate to Priority 1 immediately.