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: 0.4% (34th percentile of EPSS-scored CVEs). 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: 0.4%CVSS: 8.7Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

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
8.7HIGHmedium confidence
EG Risk
70
EG Risk 70/100CISA SSVC

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%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.4%
EPSS %ILE
34th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

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 rangeFix by version rangeDependents
ruby-json2.15.2+dfsg-1 ... 2.9.1+dfsg-1 (15 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
ruby-json2.15.2+dfsg-1 ... 2.9.1+dfsg-1 (12 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
ruby-json2.15.2+dfsg-1 ... 3.0.2+dfsg-1 (10 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
ruby-json2.15.2+dfsg-1 ... 2.9.1+dfsg-1 (8 versions)
  • every version up to 2.21.2+dfsg-1: fixed in 2.21.2+dfsg-1
—
RubyGems(1)
PackageVulnerable rangeFix by version rangeDependents
json2.20.0, 2.21.0, 2.21.1
  • 2.20.0 up to 2.21.2: fixed in 2.21.2
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 44× 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.

Showing the most recent 100 of 101 total refreshes for this CVE.

  1. 2026-10-04 23:22 UTCEPSS rescore
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  1. 2026-09-17 00:53 UTCEG score recompute
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Related CVEs(same product + 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 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 0.4% probability of exploitation in the next 30 days (34th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-71847?
CVE-2026-71847 has a CVSS base score of 8.7 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-71847?
A fix for CVE-2026-71847 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-71847 are linked in the Vendor Advisories panel on this page.

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