JSON-java: JSONTokener Unbounded Numeric String Resource-Exhaustion DoS
- Exploited
- No known exploitation
- Fix
- Fixed in 20260719
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 20260719.
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 23/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
JSON-java, a Java library for parsing and generating JSON, is affected by a bug that lets a remote attacker, without logging in, send a very long numeric value that makes the parser spend excessive CPU time, which can block request-handling threads and cause denial of service. The flaw is in the JSON parser and the XML-to-JSON conversion path, and the library's strict mode and keep-strings settings do not prevent it.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
JSON-java is a reference implementation of a JSON package in Java. From version 20150729 through 20260522, JSONTokener.nextSimpleValue can accumulate unbounded numeric tokens before JSONObject.stringToNumber passes them to BigInteger or BigDecimal conversion without a length limit. An application that parses attacker-controlled JSON or XML through JSONObject, JSONArray, or XML.toJSONObject can spend super-linear CPU time converting a sufficiently long numeric literal, blocking request-handling threads and causing denial of service. Strict mode and keep-strings settings in JSONParserConfiguration do not prevent the affected conversion path. Version 20260719 limits numeric conversion length.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure17/25No login or user action needed per the CVSS vector, reachable over the network without a login · Unknown: No advisory context yet
- Reach?/20Unknown. No tracked technology or package matched
- Severity5.9/10CVSS 5.9
- No patch0/5No signal
What would change the score
- Would score about 68 if added to CISA KEV
- Would score about 63 if CISA's SSVC rates exploitation active
- Would score about 28 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 20260719.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- stleary JSON-java
From 20150729 · fixed in 20260719
Evidence 7
- Advisory
- Repository
- Repository
- Repository
- Repository
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- Repository
- Repository
Corrections
None so far.
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Questions about CVE-2026-59171
Is CVE-2026-59171 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-59171?
JSON-java: from 20150729 before 20260719.Source: cve.now feed data
How do I fix CVE-2026-59171?
Upgrade to a fixed version: 20260719.Source: cve.now feed data