CVE-2026-87768 in DateTime::Lite
Summary
by MITRE • 10/30/2026
DateTime::Lite versions before 0.8.1 for Perl allow CPU exhaustion via a per-day loop when adding seconds.
_normalize_leap_seconds crosses day boundaries one day at a time, so add(seconds => $n) on an object with a non-floating time zone takes about |$n|/86400 iterations, and nothing limits $n. The XS implementation and the pure-Perl fallback both have the loop.
An attacker who controls the number of seconds added can keep the process busy for as long as they choose.
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Analysis
by VulDB Data Team • 10/30/2026
The DateTime::Lite module for Perl contains a critical algorithmic complexity vulnerability that allows an attacker to cause CPU exhaustion through resource consumption attacks. This flaw exists in versions prior to 0.8.1 and specifically affects operations involving the addition of seconds to date-time objects when using non-floating time zones. The core issue lies within the _normalize_leap_seconds subroutine, which is responsible for handling leap second adjustments during arithmetic operations on DateTime instances. When a user attempts to add a large number of seconds to a DateTime object that utilizes a fixed or named timezone rather than floating UTC, the internal implementation iterates through each day boundary individually to correctly apply leap second corrections. This design choice results in linear time complexity relative to the magnitude of the added seconds, creating an inefficient O(n) operation where n is proportional to the number of days spanned by the input value.
The technical mechanism of this vulnerability relies on the fact that there is no upper limit imposed on the integer value passed as the seconds parameter during addition operations. If an attacker can control or influence the magnitude of the seconds argument, they can supply a sufficiently large positive or negative integer to force the application into an infinite-appearing loop. For instance, adding approximately 86400 seconds results in one iteration through the day boundary logic, while adding significantly larger values such as millions or billions of seconds forces the CPU to perform thousands or even hundreds of thousands of iterations before completing the calculation. Since both the XS implementation and the pure-Perl fallback share this same looping structure, the vulnerability persists regardless of whether the system is running with optimized C extensions or falling back to interpreted Perl code. This ensures that the denial-of-service condition can be triggered in any deployment configuration utilizing these versions of DateTime::Lite.
From an operational perspective, this vulnerability poses a significant risk to server stability and availability. Because the loop consumes CPU cycles without yielding control until completion, it effectively blocks other processes or threads within the same application environment from executing their tasks efficiently. In web applications where DateTime manipulation is common for parsing timestamps, scheduling events, or calculating durations, an attacker could exploit this by submitting crafted requests that trigger large second additions in background jobs, API endpoints, or scheduled cron-like tasks. The resulting CPU saturation can lead to service degradation, increased latency for legitimate users, and potentially complete unavailability of the affected application if multiple such requests are processed concurrently. This aligns with CWE-400, which classifies this as a resource exhaustion vulnerability due to an algorithmic flaw that allows excessive consumption of computational resources.
The attack vector is categorized under ATT&CK technique T1496, known as Resource Hijacking, specifically within the context of CPU or memory exhaustion via inefficient algorithms. Unlike traditional buffer overflow exploits that compromise confidentiality or integrity, this vulnerability targets availability by exploiting poor algorithmic efficiency in a commonly used library. Mitigation strategies primarily involve upgrading to DateTime::Lite version 0.8.1 or later, where the developers have addressed this inefficiency by optimizing the leap second normalization process to avoid per-day iteration loops. For organizations unable to immediately upgrade, implementing input validation to restrict the maximum allowable value for seconds in addition operations can serve as a temporary compensating control. Additionally, deploying runtime monitoring tools that detect prolonged CPU usage spikes associated with DateTime arithmetic functions may help identify and terminate malicious requests before they cause significant harm. It is also advisable to review codebases for any direct exposure of second-addition parameters from untrusted sources and enforce strict bounds checking on all temporal calculations involving large intervals.