VulnerabilityPublished 9 Nov 2026

CVE-2026-59171: JSON-java · JSONTokener Has Unbounded Numeric String Resource-Exhaustion DoS

Affects org.json:jsonSource GCVE Database

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Mentioned vulnerabilities

Authoritative record:CVE-2026-59171· Medium 5.9

Not known to be exploited · CVSS 5.9 Medium : upgrade to 20260719 when convenient.

Data as of 9 Nov 2026, 23:24 UTC

CVSS 3.1 base score

5.9Medium

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	5.9

EPSS: 0.5% chance of exploitation in 30 days – higher than 46% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 20260719

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 6 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 9 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade org.json:json to 20260719.

Affected software

Product	Affected	Fixed in
Mavenorg.json:json	Affected >=20150729 <20260719	Fixed in 20260719

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Description

## 1. Executive Summary JSON-java version 20260522 contains an unguarded path from an HTTP request body to unbounded `BigInteger` and `BigDecimal` construction. `JSONTokener.nextSimpleValue()` accumulates numeric characters into a `StringBuilder` with no length cap, then passes the full string to `JSONObject.stringToNumber()`, which calls `new BigInteger(val)` or `new BigDecimal(val)` directly. Both constructors have polynomial time complexity (O(n^1.585) for `BigInteger`). A 488 KB JSON body — well within nginx's default 1 MB body-size limit — contains a 500,000-digit numeric literal that blocks the handling thread for approximately 3 seconds. Spring Boot has no default size limit for `application/json` request bodies. No parser configuration option (`withStrictMode`, `withKeepStrings`) prevents this. All three primary entry points are affected: `new JSONObject(String)`, `new JSONArray(String)`, and `XML.toJSONObject(String)`. This vulnerability is distinct from CVE-2023-5072 (which addressed `StackOverflowError` from deeply nested JSON *structures* via a `try/catch` in `nextValue()`) and from CVE-2022-45688 (which addressed recursive XML nesting depth). The numeric string length issue has been present since BigInteger support was introduced in release 20150729 and has never been fixed in any subsequent release. **Attack Complexity is rated High** because successful exploitation requires the target application to be using org.json specifically (rather than the default Jackson library used by Spring Boot), and requires the developer to have explicitly passed user-controlled input to `new JSONObject()` or equivalent. These are deployment conditions beyond the attacker's control. See Section 6 for the full CVSS rationale and Section 8 for the comparison with Jackson's treatment of the same issue class. This vulnerability was **reproduced locally against json-20260522.jar** with full evidence provided below. --- ## 2. Vulnerability Description `JSONTokener.nextSimpleValue()` accumulates characters into a `StringBuilder` with no length limit until it hits a structural JSON character: **`JSONTokener.java:500–504`:** ```java StringBuilder sb = new StringBuilder(); while (c >= ' ' && ",:]}/\\\"[{;=#".indexOf(c) < 0) { sb.append(c); // unbounded — no length check c = this.next(); } ``` The accumulated string is passed to `JSONObject.stringToValue()` → `stringToNumber()`, which calls `new BigInteger(val)` with zero size guard: **`JSONObject.java:2738`:** ```java BigInteger bi = new BigInteger(val); // val can be arbitrarily large; no guard ``` `BigInteger(String)` has O(n^1.585) time complexity due to its internal Karatsuba multiplication during construction. A 100,000-digit input takes ~120 ms; a 1,000,000-digit input takes ~12 seconds. The decimal path (`new BigDecimal(val)`, reached when the string contains a `.` or exponent) is equally affected. **No configuration option prevents this.** `withStrictMode(true)` and `withKeepStrings(true)` are not checked in the `nextSimpleValue()` → `stringToNumber()` call chain. Confirmed by execution: both options still produce BigInteger in ~120 ms for a 100K-digit input. **Relationship to CVE-2023-5072:** CVE-2023-5072 (fixed in release 20231013) catches `StackOverflowError` thrown by deeply nested JSON *structures* (`{[` brackets) inside `nextValue()`: ```java } catch (StackOverflowError e) { throw new JSONException("JSON Array or Object depth too large to process.", e); } ``` This fix is in `nextValue()` and covers only recursive object/array structure depth. It has no effect on the numeric string length path in `nextSimpleValue()` → `stringToNumber()`. The BigInteger length issue was not addressed in 20231013 or in any subsequent release. --- ## 3. Affected Code Locations | File | Lines | Description | |------|-------|-------------| | `JSONTokener.java` | 500–504 | `nextSimpleValue()` — unbounded character accumulation into `StringBuilder`, no length cap | | `JSONObject.java` | 2721–2748 | `stringToNumber()` — `new BigInteger(val)` / `new BigDecimal(val)` called directly with no length guard | --- ## 4. Proof of Concept (Locally Verified) ### 4.1 POC Code ```java import org.json.*; public class Poc2NumericDoSv2 { public static void main(String[] args) { System.out.println("=== CVE-002: JSONTokener Unbounded Numeric String DoS ==="); // Scaling: timing at different digit counts System.out.println("\n-- Unquoted numeric literal (JSONObject) --"); int[] sizes = {10_000, 100_000, 200_000, 500_000, 1_000_000}; for (int numLen : sizes) { String payload = "{\"x\":" + "9".repeat(numLen) + "}"; long start = System.currentTimeMillis(); JSONObject jo = new JSONObject(payload); long elapsed = System.currentTimeMillis() - start; System.out.printf(" %,7d digits (~%3d KB): %,5d ms type=%s%n", numLen, payload.length()/1024, elap

CWE-400Uncontrolled Resource Consumption (opens in a new tab)
Class weaknessLikelihood of exploit: High
The product does not properly control the allocation and maintenance of a limited resource.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place.
Architecture and Design
Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or; uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed.
Architecture and Design
Ensure that protocols have specific limits of scale placed on them.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
Attack patterns
XML Ping of the Death (opens in a new tab)
Regular Expression Exponential Blowup (opens in a new tab)
Sustained Client Engagement (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-770Allocation of Resources Without Limits or Throttling (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #25
The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
Requirements
Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
Architecture and Design
Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
Architecture and Design
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V8.1.4 (opens in a new tab)
V13.4.1 (opens in a new tab)
V11.1.4 (opens in a new tab)
Attack patterns
XML Ping of the Death (opens in a new tab)
Exponential Data Expansion (opens in a new tab)
Serialized Data Parameter Blowup (opens in a new tab)
Serialized Data with Nested Payloads (opens in a new tab)
Oversized Serialized Data Payloads (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

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Exploitation evidence

What to do

Affected software

Description

WeaknessesCWE-400, CWE-770

Technical details

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