CVE-2026-71847Public exploitNetwork attack vector

Process termination via stale parser-state pointers

Published Aug 7, 2026 · Updated Aug 7, 2026

Use-after-free in Ruby JSON 2.20.0 through 2.21.1 allows remote attackers to terminate Ruby processes via crafted JSON streams. JSON::ResumableParser clears its consumed input buffer without resetting state.start, state.cursor, and state.end, so partial_value sends stale pointers to cursor_position when rebuilding an incomplete object with duplicate keys. Reachability requires attacker-controlled streaming input, JSON::ResumableParser, and a partial_value call on the incomplete object; the demonstrated consequence is process termination only.

CVSS severity8.7
High
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Ruby JSON 2.20.0 through 2.21.1 allows remote attackers to terminate Ruby processes via crafted JSON streams. JSON::ResumableParser clears its consumed input buffer without resetting state.start, state.cursor, and state.end, so partial_value sends stale pointers to cursor_position when rebuilding an incomplete object with duplicate keys. Reachability requires attacker-controlled streaming input, JSON::ResumableParser, and a partial_value call on the incomplete object; the demonstrated consequence is process termination only.

The record

CVE
CVE-2026-71847
Published
Aug 7, 2026
Updated
Aug 7, 2026
Vendor
Ruby
Product
JSON
Classifications
CWE-416, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 7, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 2.20.0, < 2.21.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Ruby · JSONversion=>= 2.20.0, < 2.21.2

Published CVSS scores

8.7GitHub CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-416Use After Free
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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