Vulnerability in json (CVE-2026-54696)
Summary
Vulnerability in json (CVE-2026-54696). Risk of unauthorized operations or information disclosure. Exploitable via FBUFFER_IO_BUFFER_SIZE. Mitigation: upgrade to 2.19.9 or later.
Original description
The description as published by the source.
Ruby JSON is a JSON implementation for Ruby. Versions 2.9.0 through 2.19.8 are vulnerable to heap buffer overflow when the JSON generator is provided with an oversized streamed object. When streaming to an IO JSON.dump(obj, io) and JSON::State#generate(obj, io) can write past the internal JSON generator buffer when a streamed object contains an
attacker-controlled string near 16 KB. Exploitation would result in a reliable process crash/denial of service. This issue has been fixed in version 2.19.9.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-54696 has been found in json.
Attackers can target a specific entry point like FBUFFER_IO_BUFFER_SIZE over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 3.7/10.
What to do: upgrade json to 2.19.9 or later.
If unsure, ask your IT team or search "json CVE-2026-54696" on the vendor's site.
CVE-2026-54696 (json) — CWE-122 / CVSS v3 3.7
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: FBUFFER_IO_BUFFER_SIZE
Patched: 2.19.9 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-122) exists in json. Attackers reach the vulnerable code path via FBUFFER_IO_BUFFER_SIZE without authentication.
Check the vendor advisory for the affected versions of json. Attack surface: FBUFFER_IO_BUFFER_SIZE.
Severity: Low (CVSS 3.7/10). Risk of unauthorized operations or information disclosure.
Update to 2.19.9.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'json' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'json' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
jsonを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade json to 2.19.9ステージング環境で 2.19.9 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-54696 ruby-json
- Ubuntu UBUNTU-CVE-2026-54696 jruby
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- web github.com
- web github.com
- web github.com
- web github.com