Vulnerability in json-web-token (CVE-2023-48238)
Summary
Vulnerability in json-web-token (CVE-2023-48238). Data can be tampered with by attackers. Exploitable via decode. Mitigation: upgrade to 4.0.0 or later.
Original description
The description as published by the source.
joaquimserafim/json-web-token is a javascript library use to interact with JSON Web Tokens (JWT) which are a compact URL-safe means of representing claims to be transferred between two parties. Versions prior to 4.0.0 are vulnerable to a JWT algorithm confusion attack. On line 86 of the 'index.js' file, the algorithm to use for verifying the signature of the JWT token is taken from the JWT token, which at that point is still unverified and thus shouldn't be trusted. To exploit this vulnerability, an attacker needs to craft a malicious JWT token containing the HS256 algorithm, signed with the public RSA key of the victim application. This attack will only work against this library is the RS256 algorithm is in use, however it is a best practice to use that algorithm. Version 4.0.0 fixes the issue.
Source: GitHub Security Advisories (Global) 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-2023-48238 has been found in json-web-token.
Attackers can target a specific entry point like decode over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 7.5/10.
What to do: upgrade json-web-token to 4.0.0 or later.
If unsure, ask your IT team or search "json-web-token CVE-2023-48238" on the vendor's site.
CVE-2023-48238 (json-web-token) — CWE-20 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: decode
Patched: 4.0.0 — 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-20) exists in json-web-token. Attackers reach the vulnerable code path via decode without authentication.
Check the vendor advisory for the affected versions of json-web-token. Attack surface: decode.
Severity: High (CVSS 7.5/10). Data can be tampered with by attackers.
Update to 4.0.0.
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-web-token' . 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-web-token' . | 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-web-token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-web-token to 4.0.0ステージング環境で 4.0.0 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
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- patch github.com
- web github.com
- web github.com