CVE-2024-2613: Mozilla Firefox DOS Vulnerability

CVE-2024-2613 Overview

CVE-2024-2613 is a denial-of-service vulnerability in Mozilla Firefox affecting versions prior to 124. The flaw stems from improper data sanitization when decoding a QUIC ACK frame. A remote attacker can trigger unrestricted memory consumption, leading to a browser crash. The vulnerability requires no authentication and no user interaction beyond initiating a network connection processed by the affected QUIC implementation. Mozilla addressed the issue in Firefox 124 through advisory MFSA-2024-12.

Critical Impact
Remote attackers can exhaust memory and crash Firefox by sending malformed QUIC ACK frames, disrupting browser availability without authentication or user interaction.

Affected Products

Mozilla Firefox versions prior to 124
Components processing QUIC ACK frame decoding
Mozilla browser products relying on the vulnerable QUIC stack

Discovery Timeline

2024-03-19 - CVE-2024-2613 published to NVD
2025-02-25 - Last updated in NVD database

Technical Details for CVE-2024-2613

Vulnerability Analysis

The vulnerability resides in the QUIC transport layer implementation used by Firefox. QUIC is a UDP-based transport protocol that underpins HTTP/3. ACK frames in QUIC acknowledge received packets and include ranges of packet numbers. The Firefox decoder failed to properly sanitize fields contained in an incoming ACK frame. An attacker controlling a remote QUIC endpoint can craft an ACK frame that forces the browser to allocate unbounded memory during decoding. The classification [CWE-1021] reflects an improper restriction issue. The available impact metrics indicate a network-reachable condition affecting availability only, with no compromise of confidentiality or integrity.

Root Cause

The root cause is missing input validation on QUIC ACK frame fields prior to memory allocation. When the decoder processes attacker-controlled ranges or gap values without bounding checks, it expands internal data structures without limit. This pattern results in resource exhaustion and eventual process termination.

Attack Vector

Exploitation occurs over the network. An attacker hosts a malicious QUIC endpoint or intercepts a QUIC session and returns a crafted ACK frame containing values that drive the decoder into excessive allocation. The victim browser must initiate or accept a QUIC connection with the attacker-controlled endpoint, which typically happens when a user navigates to a malicious site that negotiates HTTP/3.

No verified exploit code is publicly available. Technical details are described in the Mozilla Bug Report #1875701 and Mozilla Security Advisory MFSA-2024-12.

Detection Methods for CVE-2024-2613

Indicators of Compromise

Repeated Firefox process crashes correlated with outbound UDP traffic on port 443
Unusually high resident memory growth in firefox.exe or firefox processes during web browsing
Crash reports referencing QUIC or HTTP/3 components in about:crashes
Connections to untrusted hosts negotiating HTTP/3 followed by browser termination

Detection Strategies

Monitor endpoint telemetry for Firefox process exits with abnormal memory peaks preceding termination
Inspect network logs for HTTP/3 sessions to low-reputation domains followed by client-side disconnects
Deploy software inventory checks to flag Firefox installations below version 124
Correlate browser crash dumps with QUIC connection metadata captured by network sensors

Monitoring Recommendations

Track Firefox version distribution across managed endpoints and alert on out-of-date installs
Capture UDP/443 flow records to identify clients communicating with suspicious QUIC servers
Aggregate browser crash telemetry centrally to spot clusters indicating active exploitation attempts
Review proxy and DNS logs for navigation patterns preceding repeated browser failures

How to Mitigate CVE-2024-2613

Immediate Actions Required

Update Mozilla Firefox to version 124 or later on all managed endpoints
Apply equivalent updates to Firefox ESR, Thunderbird, and other Mozilla products incorporating the same QUIC stack
Enforce automatic browser updates through enterprise policy where supported
Restart browser sessions after patching to ensure the vulnerable code is unloaded

Patch Information

Mozilla released fixes in Firefox 124. Refer to Mozilla Security Advisory MFSA-2024-12 for the complete list of addressed issues and patched builds. The supporting bug is tracked in Mozilla Bug Report #1875701.

Workarounds

Disable HTTP/3 by setting network.http.http3.enabled to false in about:config until patching completes
Block outbound UDP/443 at the network perimeter for endpoints that cannot be updated immediately
Restrict browsing to trusted destinations through web filtering policies
Restart Firefox after configuration changes to apply the workaround

bash

# Disable HTTP/3 in Firefox via policies.json
{
  "policies": {
    "Preferences": {
      "network.http.http3.enabled": {
        "Value": false,
        "Status": "locked"
      }
    }
  }
}