CVE-2026-71847

HIGHPre-NVD 8.78.7—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 74% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
8.7EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.7Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Ruby JSON is a JSON implementation for Ruby. From 2.20.0 until 2.21.2, Ruby's JSON native C extension clears the consumed JSON::ResumableParser input buffer but leaves state.start, state.cursor, and state.end pointing into released storage. When partial_value reconstructs an incomplete object containing duplicate keys, the duplicate-key warning path calls cursor_position, which dereferences those stale pointers. This results in a heap-use-after-free and can terminate the Ruby process. An attacker who can supply JSON stream data to an application using JSON::ResumableParser may cause process termination when the application calls partial_value on incomplete attacker-controlled input containing duplicate object keys. This issue has been fixed in version 2.21.2.

CVSS v3
8.7
EG Score
8.7(medium)
EG Risk
70(Attend)
EG Risk 70/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity87% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
26%
KEV
Not listed

Published

August 7, 2026

Last Modified

September 18, 2026

Advisory Details (1)

Auto-updated Aug 7, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

JSON::ResumableParser#partial_value dereferences a freed input buffer and crashes on truncated duplicate-key streams · Advisory · ruby/json · GitHub

https://github.com/ruby/json/security/advisories/GHSA-9hj4-r449-hfvc

Vendor Advisories for CVE-2026-71847(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
ruby-json2.15.2+dfsg-1 ... 2.9.1+dfsg-1 (15 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
ruby-json2.15.2+dfsg-1 ... 2.9.1+dfsg-1 (12 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
ruby-json2.15.2+dfsg-1 ... 2.9.1+dfsg-1 (9 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
ruby-json2.15.2+dfsg-1 ... 2.9.1+dfsg-1 (8 versions)2.21.2+dfsg-1—
RubyGems(1)
PackageVulnerable rangeFixed inDependents
json2.20.0, 2.21.0, 2.21.12.21.2—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 49× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-18 20:11 UTCEG score recompute
  2. 2026-09-18 19:28 UTCEPSS rescore
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  1. 2026-09-03 05:59 UTCEG score recompute
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  39. 2026-08-13 23:13 UTCEG score recompute
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  43. 2026-08-11 18:36 UTCEG score recompute
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  45. 2026-08-11 00:00 UTCEPSS rescore
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  47. 2026-08-09 13:47 UTCEPSS rescore
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  49. 2026-08-08 16:37 UTCEPSS rescore
  50. 2026-08-07 22:33 UTCEG score recompute
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  52. 2026-08-07 19:28 UTCEG score recompute
  53. 2026-08-07 18:47 UTCEG score recompute
  54. 2026-08-07 18:47 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-71847?
CVE-2026-71847 is a high vulnerability published on August 7, 2026. Ruby JSON is a JSON implementation for Ruby. From 2.20.0 until 2.21.2, Ruby's JSON native C extension clears the consumed JSON::ResumableParser input buffer but leaves state.start, state.cursor, and state.end pointing into released storage. When partialvalue reconstructs an incomplete object…
When was CVE-2026-71847 disclosed?
CVE-2026-71847 was first published in the National Vulnerability Database on August 7, 2026, with the most recent update on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-71847 actively exploited?
CVE-2026-71847 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 73.7% of all scored CVEs.
What is the CVSS score of CVE-2026-71847?
CVE-2026-71847 has a CVSS v3 base score of 8.7 (NVD).
How do I remediate CVE-2026-71847?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-71847, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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