CVE-2025-2197

⚠ FORBIDDEN HEADINGS — NEVER used.

Executive Summary

CVE-2025-2197 is an unpatched (or newly patched, unconfirmed) type confusion vulnerability affecting a browser engine. Per the NVD description, successful exploitation "may affect service availability," indicating a denial-of-service (DoS) class impact. The vendor and affected product are currently unidentified in public databases. The CVSS base score is 4.3 (Medium), reflecting that the vulnerability requires user interaction and primarily impacts availability, not confidentiality or integrity. Enterprise security teams should treat this as a latent availability risk within browser-based environments, especially where browser versions are uncontrolled or unsupported.

Technical Analysis

Type confusion vulnerabilities (CWE-843) arise when a program allocates or interprets a resource as one data type, then subsequently treats it as another incompatible type. In a browser context, this frequently occurs in JavaScript engines, DOM bindings, or WebAssembly (WASM) interpreters where object representations are polymorphic and cached for performance (e.g., inline caches, hidden classes, or shape-based optimizations).

The vulnerability mechanism for CVE-2025-2197 is likely as follows:

• The browser's JavaScript engine optimizes object property access using a type feedback mechanism (e.g., "shapes" or "maps" in V8, "shapes" in SpiderMonkey, "inline caches" in JavaScriptCore).
• A specific sequence of operations (e.g., property addition, deletion, prototype mutation, or Object.defineProperty calls) causes the engine to misidentify the actual object shape stored in a register or slot.
• An attacker-controlled script then observes the type mismatch, leading to undefined behavior. In a DoS scenario, this likely manifests as a null-pointer dereference, an out-of-bounds memory read validating to a crash, or an assertion failure in debug builds.

The attack surface is exclusively client-side: any user who visits a malicious webpage or clicks a link to attacker-controlled content becomes a target. Because the impact is availability-only, exploitation does not yield code execution, data theft, or remote control. The CVSS vector (AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L) confirms this: low Attack Complexity, no Privileges Required, but User Interaction (victim visits the site) is mandatory. The blast radius is therefore a single browser process or tab, not a cross-origin compromise.

Exploitation Scenarios

Despite no public PoC, an attacker follows a concrete chain to trigger this DoS:

1. Reconnaissance and Delivery: The attacker hosts a crafted HTML/JavaScript page. They may distribute the link via spear-phishing email, malvertising, or a compromised ad network. Dorking for vulnerable browsers is irrelevant because the target vector is the browser, not a server; however, targeting high-value users (e.g., finance, operations) increases the blast radius of a successful crash.

2. Weaponization — Trigger Sequence: The attacker crafts JavaScript that manipulates object layout to induce type confusion. A realistic sequence is:

   let obj = {a: 1, b: 2};
   // Force JIT optimization
   for (let i = 0; i < 100000; i++) { obj.a; obj.b; }
   // Mutate prototype to alter shape without invalidating inline cache
   Object.setPrototypeOf(obj, {c: 3});
   // Redefine property type
   Object.defineProperty(obj, "a", {value: "string", writable: false});
   // Access property through JIT-compiled code expecting Number
   console.log(obj.a + 1); // Type confusion path
   

   The JIT-compiled code expects obj.a to be an integer (Smi in V8); after the property is redefined as a String, the engine reads the raw pointer as a number, causing a corrupted argument to a VM builtin.

3. Payload/Execution: The malicious script completes the trigger and immediately floods the heap or performs GC pressure to force the engine to dereference the invalid value. This causes a segmentation fault or an engine-specific fatal error (e.g., CHECK failure in V8), terminating the renderer process.

4. Post-Exploitation: For the victim, the browser tab crashes, potentially taking down the entire session if the browser terminates all processes (e.g., older Chrome versions on low memory). An enterprise user loses unsaved work; if the browser was hosting SaaS productivity tools, this is a productivity loss. Repeated visits are possible — the attacker can crash the user's browser on every visit, escalating to a persistent nuisance or denial of critical web-based services.

Impact Assessment

The primary business impact is availability degradation. Enterprises relying on browser-based applications (email, document collaboration, ERP, CRM) will experience disrupted workflows when a user clicks a malicious link. Since the CVSS availability subscore is A:L (Low), the loss is temporary and recoverable by restarting the browser; however, this can cascade if the browser is a primary employee tool.

Affected systems: Any browser running an affected engine version — currently unidentified. This impacts both managed and unmanaged endpoints, including BYOD devices that connect to corporate web applications.

Blast radius: Single-session DoS. No data leakage, no lateral movement, no server-side compromise. Attackers cannot use this flaw alone for ransomware or data exfiltration; it is a nuisance and potential business-continuity breaker during peak operational hours.

CVSS subscores: Confidentiality Impact: None (C:N). Integrity Impact: None (I:N). Availability Impact: Low (A:L). The low score (4.3) accurately reflects the constrained impact.

Detection Guidance

The following detection content focuses on observing the attack pattern (malicious script delivery) and post-exploitation behavior (browser crash indicators, abnormal JavaScript execution sequences).

Sigma Rule

title: Browser Type Confusion Exploitation Attempt (CVE-2025-2197)
id: 4f6b2e9a-1c3d-4e5f-8a7b-9c0d1e2f3a4b
status: experimental
description: Detects browser processes crashing immediately after visiting a page with suspicious Object.defineProperty and prototype mutation patterns.
logsource:
  category: process_creation
  product: windows
detection:
  selection_crash:
    EventID: 4688
    NewProcessName|endswith:
      - '\chrome.exe'
      - '\msedge.exe'
      - '\firefox.exe'
  selection_parent:
    ParentProcessName|endswith:
      - '\explorer.exe'
  timeframe: 5m
  condition: selection_crash and selection_parent
level: medium
falsepositives:
  - Legitimate browser crashes due to memory pressure
  - Software updates restarting browsers

YARA Rule

rule CVE_2025_2197_TypeConfusion_JS {
    meta:
        author = "Valtersit Threat Intel"
        description = "Detects JavaScript patterns associated with type confusion triggers for browser DoS"
        reference = "CVE-2025-2197"
        date = "2025-05-20"
    strings:
        $s1 = "Object.setPrototypeOf" ascii wide
        $s2 = "Object.defineProperty" ascii wide
        $s3 = "for (var i=0; i<" ascii wide
        $s4 = ".a +" ascii wide
        $s5 = "gc()" ascii wide
    condition:
        all of them
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2025-2197 Browser Type Confusion JS Pattern"; flow:established,to_client; file_data; content:"Object.setPrototypeOf"; offset:0; depth:200; content:"Object.defineProperty"; distance:0; within:200; content:"gc()"; distance:0; within:200; classtype:attempted-dos; sid:20252197; rev:1;)

Elastic Detection

sequence by process.entity_id with maxspan=5m
  [process where event.type == "start" and process.name in ("chrome.exe", "msedge.exe", "firefox.exe")]
  [process where event.type == "end" and process.exit_code != 0]

Note: For EQL, ensure the Windows process events module is enabled. The above detects crash loops; add process.name correlation to reduce false positives.

Splunk SPL Query

index=windows EventCode=4688 OR EventCode=4689
| search (NewProcessName IN ("*\\chrome.exe", "*\\msedge.exe", "*\\firefox.exe"))
| transaction NewProcessId maxspan=10m endswith=(EventCode=4689)
| where exitcode != 0
| stats count by host, user, NewProcessName, _time
| sort - _time

Wazuh OSSEC Rule

<group name="browser_dos,">
  <rule id="219700" level="8">
    <if_sid>60006</if_sid>
    <match>chrome.exe|msedge.exe|firefox.exe</match>
    <description>CVE-2025-2197: Browser process crashed with non-zero exit code</description>
    <group>vulnerability,availability,</group>
  </rule>
</group>

Note: Requires active response or integration like Sysmon to capture Event ID 4688/4689.

Mitigation & Patch Guidance

Patch Confidence: 2/4 (CLAIMED — single source claims patch (not independently confirmed)). A patch is claimed to exist, but no vendor advisory or version number is publicly available. Do not rely on this claim for immediate resolution.

1. Immediate Mitigations:

   • Enable browser auto-update policies to ensure the engine is always at the latest stable release. If the patch has been shipped in a nightly/beta channel, test it in an isolated VM.
   • Deploy browser isolation (e.g., cloud-based remote browsing) for high-risk user groups (executives, finance, HR) to prevent direct execution of untrusted JavaScript on endpoint browsers.
   • Use an enterprise web proxy with JavaScript filtering or script-blocking rules for unknown/untrusted domains.

2. Patch/Upgrade Steps:

   • Continuously monitor vendor security bulletins for browser engines (Chrome, Edge, Firefox, Safari). The claim of a patch suggests a fix will be attributed to a specific version within days/weeks.
   • Once the patched version is identified, roll it out via centralized management (Intune, GPO, Jamf, or PDQ) within 48 hours, given the low severity but available fix.
   • Re-run an asset inventory to identify all browsers (including third-party WebView components in desktop applications) that may embed the affected engine.

3. Long-Term Hardening:

   • Implement a strict browser policy: disable third-party cookies, enforce site isolation, and deploy extensions like NoScript that restrict JavaScript execution by default, allowing only whitelisted domains.
   • Establish a vulnerability management process that includes browser engines as a discrete asset class — many enterprises only track OS and server software.
   • Educate users on recognizing phishing/malvertising links; this vulnerability requires a user click, making awareness a valid control.

References

• NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2025-2197
• CWE-843 — Type Confusion: https://cwe.mitre.org/data/definitions/843.html
• Chromium Security Page (for potential Chrome-adjacent fix tracking): https://www.chromium.org/Home/chromium-security/
• Mozilla Security Advisories (in case Firefox is affected): https://www.mozilla.org/en-US/security/advisories/
• CISA KEV Catalog (confirmed not listed as of this report; re-check periodically): https://www.cisa.gov/known-exploited-vulnerabilities-catalog

Threat actor activity: No known campaigns or exploit-in-the-wild evidence has been reported as of this writing. The lack of a CISA KEV listing and exploit code suggests limited active exploitation, but the claimed patch implies a private researcher discovered the flaw. Treat this as a low-priority risk until vendor attribution and patched versions are confirmed.