CVE-2018-5144 in Firefox
Summary
by MITRE
An integer overflow can occur during conversion of text to some Unicode character sets due to an unchecked length parameter. This vulnerability affects Firefox ESR < 52.7 and Thunderbird < 52.7.
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Analysis
by VulDB Data Team • 11/26/2025
The vulnerability identified as CVE-2018-5144 represents a critical integer overflow flaw that manifests during text conversion processes to Unicode character sets within Mozilla Firefox ESR versions prior to 52.7 and Thunderbird versions before 52.7. This issue stems from an unchecked length parameter that fails to properly validate input boundaries during character encoding transformations. The flaw specifically targets the handling of text data when converting to Unicode formats, creating a scenario where maliciously crafted input can trigger unexpected behavior in the application's memory management systems.
The technical implementation of this vulnerability involves a fundamental flaw in how the affected applications process text data during Unicode conversion operations. When text is processed through the affected code paths, the system does not adequately validate the length parameter before performing arithmetic operations that could result in integer overflow conditions. This overflow occurs because the application attempts to perform calculations using values that exceed the maximum representable integer limits for the target data type, leading to unpredictable memory access patterns and potential exploitation opportunities.
From an operational perspective, this vulnerability poses significant risks to users of the affected software versions, as it can be exploited to execute arbitrary code on vulnerable systems. Attackers can craft malicious text content that when processed by Firefox or Thunderbird triggers the integer overflow condition, potentially allowing for remote code execution or denial of service attacks. The impact extends beyond simple application instability since the overflow can corrupt memory structures and potentially provide attackers with elevated privileges or system control. This vulnerability directly relates to CWE-190, which categorizes integer overflow conditions as a critical class of software defects that can lead to memory corruption and exploitation.
The exploitation of CVE-2018-5144 aligns with several techniques documented in the MITRE ATT&CK framework under the 'Execution' and 'Memory Injection' tactics. The vulnerability can be leveraged to achieve code execution through memory corruption techniques that are commonly associated with integer overflow exploits. Security researchers have noted that such flaws are particularly dangerous in web browsers due to the extensive text processing capabilities and the potential for cross-site scripting attacks that can trigger these conditions. The vulnerability's impact is amplified by the widespread use of affected browser versions, making it a prime target for exploit development and deployment in the wild.
Organizations and users should immediately apply the security patches released by Mozilla for Firefox ESR 52.7 and Thunderbird 52.7 to mitigate this vulnerability. The fix involves implementing proper bounds checking and input validation for length parameters during Unicode conversion operations, ensuring that integer arithmetic operations remain within safe computational limits. Additional defensive measures include implementing network segmentation, monitoring for unusual text processing patterns, and maintaining updated threat intelligence feeds to detect potential exploitation attempts. System administrators should also consider implementing application whitelisting policies and restricting user access to potentially malicious content that could trigger these integer overflow conditions.