This High severity DoS (Denial of Service) vulnerability was introduced in version 10.3.14 of Jira Service Management Data Center and Server.

This vulnerability with a CVSS Score of 8.7 and a CVSS Vector of CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X allows an unauthenticated attacker to expose assets in your environment susceptible to exploitation which has no impact to confidentiality, no impact to integrity, high impact to availability, and requires no user interaction. 

Atlassian recommends that Jira Service Management Data Center and Server customers upgrade to latest version, if you are unable to do so, upgrade your instance to one of the specified supported fixed versions:

• Jira Service Management Data Center and Server 10.3: Upgrade to a release greater than or equal to 10.3.16

See the release notes. You can download the latest version of Jira Service Management Data Center and Server from the download center.

The National Vulnerability Database provides the following description for this vulnerability: Improper Input Validation vulnerability in qs (parse modules) allows HTTP DoS.This issue affects qs: < 6.14.1. SummaryThe arrayLimit option in qs does not enforce limits for bracket notation (a[]=1&a[]=2), allowing attackers to cause denial-of-service via memory exhaustion. Applications using arrayLimit for DoS protection are vulnerable. DetailsThe arrayLimit option only checks limits for indexed notation (a[0]=1&a[1]=2) but completely bypasses it for bracket notation (a[]=1&a[]=2). Vulnerable code (lib/parse.js:159-162): if (root === '[]' && options.parseArrays) { obj = utils.combine([], leaf); // No arrayLimit check } Working code (lib/parse.js:175): else if (index <= options.arrayLimit) { // Limit checked here obj = []; obj[index] = leaf; } The bracket notation handler at line 159 uses utils.combine([], leaf) without validating against options.arrayLimit, while indexed notation at line 175 checks index <= options.arrayLimit before creating arrays. PoCTest 1 - Basic bypass: npm install qs const qs = require('qs'); const result = qs.parse('a[]=1&a[]=2&a[]=3&a[]=4&a[]=5&a[]=6', { arrayLimit: 5 }); console.log(result.a.length); // Output: 6 (should be max 5) Test 2 - DoS demonstration: const qs = require('qs'); const attack = 'a[]=' + Array(10000).fill('x').join('&a[]='); const result = qs.parse(attack, { arrayLimit: 100 }); console.log(result.a.length); // Output: 10000 (should be max 100) Configuration: * arrayLimit: 5 (test 1) or arrayLimit: 100 (test 2) * Use bracket notation: a[]=value (not indexed a[0]=value) ImpactDenial of Service via memory exhaustion. Affects applications using qs.parse() with user-controlled input and arrayLimit for protection. Attack scenario: * Attacker sends HTTP request: GET /api/search?filters[]=x&filters[]=x&...&filters[]=x (100,000+ times) * Application parses with qs.parse(query, { arrayLimit: 100 }) * qs ignores limit, parses all 100,000 elements into array * Server memory exhausted → application crashes or becomes unresponsive * Service unavailable for all users Real-world impact: * Single malicious request can crash server * No authentication required * Easy to automate and scale * Affects any endpoint parsing query strings with bracket notation