CVE-2023-48238

Description

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. Affected versions of the json-web-token library 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.

Description (MITRE) cveawg.mitre.org

Pulled from cveawg.mitre.org/api/cve/CVE-2023-48238 on 2026-07-28. Shown when MITRE's text differs from the cvelistV5 mirror.

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.

Overview

State: PUBLISHED
Assigner (CNA): GitHub_M
CVSS severity: HIGH
CVSS score: 7.5 / 10
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Effective score: 7.5 / 10 HIGH source: CNA overview
CWE(s): CWE-345
Reserved: 2023-11-13
Published: 2023-11-17 22:35 UTC
Last updated: 2024-10-11 17:24 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2023/48xxx/CVE-2023-48238.json
Linked Threat: CVE-2023-48238 — JWT Algorithm Confusion in json-web-token library

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2023-11-17 22:15:07 UTC
NVD last modified: 2026-06-17 06:33:48 UTC
NVD CVSS v3.1: 7.5 / 10 HIGH source: security-advisories@github.com
NVD CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Exploitability subscore: 3.9 / 10
Impact subscore: 3.6 / 10
EPSS score: 0.0030 (probability of exploitation in next 30 days)
EPSS percentile: 22.67% vs all CVEs — higher = more likely to be exploited, as of 2026-07-27

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2023-2883
Assigner: GitHub_M
Published: Nov 17, 2023, 9:35:00 PM
Updated: Oct 11, 2024, 3:24:50 PM
EUVD base score (CVSS 3.1): 7.5 / 10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
EUVD-reported EPSS: 0.1900
Vendors: joaquimserafim
Products: json-web-token (< 3.1.1)
Aliases: GHSA-4xw9-cx39-r355

ENISA description: 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. Affected versions of the json-web-token library 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.

EUVD references (1)

https://github.com/joaquimserafim/json-web-token/security/advisories/GHSA-4xw9-cx39-r355

Affected products (1)

Vendor	Product	Versions	Platforms
joaquimserafim	json-web-token	`< 3.1.1` (affected)	—

Affected products — CPE 2.3 (1) NVD

NVD's normalized CPE 2.3 matchers, used by vendor tools (vulnerability scanners, asset managers) for automated detection. Compare with the CNA's free-text "Affected products" section above.

cpe:2.3:a:joaquimserafim:json_web_token:*:*:*:*:*:node.js:*:*

Vendor references (1)

References embedded in the original CVE record by the assigning CNA.

https://github.com/joaquimserafim/json-web-token/security/advisories/GHSA-4xw9-cx39-r355 x_refsource_CONFIRM

MITRE references (2) cveawg.mitre.org

Pulled from MITRE's CVE Services API by the 🛰 Backfill from MITRE button.

https://github.com/joaquimserafim/json-web-token/commit/b6e56b1346f48432d29133c76b65222ad93956b7 x_refsource_MISC
https://github.com/joaquimserafim/json-web-token/security/advisories/GHSA-4xw9-cx39-r355 x_refsource_CONFIRM

Web references (0)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

No web references attached yet.

NVD-tagged references (3)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://github.com/joaquimserafim/json-web-token/security/advisories/GHSA-4xw9-cx39-r355 security-advisories@github.com ExploitVendor Advisory
https://github.com/joaquimserafim/json-web-token/security/advisories/GHSA-4xw9-cx39-r355 af854a3a-2127-422b-91ae-364da2661108 ExploitVendor Advisory
https://github.com/joaquimserafim/json-web-token/commit/b6e56b1346f48432d29133c76b65222ad93956b7 security-advisories@github.com

Indicators (1)

IOCs linked to the auto-promoted Threat row.

Type	Value	VirusTotal	Attached
domain	`index.js`	no local data	2026-05-18 21:20 UTC

Remediations (19)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

CISA Requires Federal Agencies to Patch Critical Vulnerabilities Within ...

web:cybersecuritynews.com

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has issued Binding Operational Directive (BOD) 26-04, titled "Prioritizing Security Updates Based on Risk," compelling all Federal Civilian Executive Branch (FCEB) agencies to remediate the most dangerous known exploited vulnerabilities within just three calendar days.

2026-06-27 17:58 UTC
NVD - Home

web:nvd.nist.gov

The NVD is the U.S. government repository of standards based vulnerability management data represented using the Security Content Automation Protocol (SCAP). This data enables automation of vulnerability management, security measurement, and compliance. The NVD includes databases of security checklist references, security-related software flaws, product names, and impact metrics. For ...

2026-06-27 17:58 UTC
Windows 11, version 23H2 known issues and notifications

web:learn.microsoft.com

As of November 11, 2025, Home and Pro editions of Windows 11, version 23H2 have reached end of servicing. Enterprise and Education editions of version 23H2 will continue to receive monthly security updates until November 10, 2026.

2026-06-27 17:58 UTC
Oracle Critical Security Patch Update Advisory - May 2026

web:www.oracle.com

This Critical Security Patch Update contains 35 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Security Patch Update and other Oracle Software Security Assurance activities is located at May 2026 Critical Security Patch Update: Executive Summary and Analysis.

2026-06-27 17:58 UTC
Microsoft is working on a patch for 'YellowKey ... - Computerworld

web:www.computerworld.com

Microsoft says it is considering a patch for a zero-day vulnerability, dubbed YellowKey, that allows attackers with access to a Windows device to bypass Bitlocker encryption protection and read ...

2026-06-27 17:58 UTC
September 2025 Patch Tuesday: Updates and Analysis | CrowdStrike

web:www.crowdstrike.com

Microsoft has released security updates for 84 vulnerabilities, including 2 publicly disclosed zero-day and 8 critical, in its September 2025 Patch Tuesday rollout.

2026-06-27 17:58 UTC
February's Patch Tuesday release fixes 59 flaws ... - Computerworld

web:www.computerworld.com

Each month, the team at Readiness analyzes the latest Patch Tuesday updates from Microsoft and provides detailed, actionable testing guidance. The company's Patch Tuesday release for February ...

2026-05-22 07:35 UTC
Microsoft March 2026 Patch Tuesday fixes 2 zero-days, 79 flaws

web:www.bleepingcomputer.com

Today is Microsoft's March 2026 Patch Tuesday with security updates for 79 flaws, including 2 publicly disclosed zero-day vulnerabilities.

2026-05-22 07:35 UTC
PDF Guide to Enterprise Patch Management Planning: - NIST

web:nvlpubs.nist.gov

The third version, SP 800-40, Revision 3, Guide to Enterprise Patch Management Technologies (2013), was written under the assumption that readers already understood the basics of patch management and that what they most needed help with was implementing, configuring, securing, and using enterprise patch management technologies.

2026-05-22 07:35 UTC
Oracle Critical Patch Update Advisory - April 2026

web:www.oracle.com

This Critical Patch Update contains 481 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at April 2026 Critical Patch Update: Executive Summary and Analysis.

2026-05-22 02:57 UTC
Microsoft Rolls Out Mitigations for 'YellowKey' BitLocker ...

web:www.securityweek.com

Microsoft has announced mitigations for CVE -2026-45585, a BitLocker bypass triggered via FsTx in Windows Recovery.

2026-05-22 02:57 UTC
Microsoft Releases Mitigation for Windows BitLocker Security Bypass 0 ...

web:cybersecuritynews.com

No patch has been released yet; Microsoft has instead issued a multi-step manual mitigation guide while a formal security update is prepared. Windows BitLocker Security Bypass The vulnerability originates in WinRE's handling of the BootExecute registry value under HKLM\ControlSet001\Control\Session Manager.

2026-05-22 02:57 UTC
GitHub - nccgroup/exploit_mitigations: Knowledge base of exploit ...

web:github.com

Knowledge base of exploit mitigations available across numerous operating systems, architectures and applications and versions. - nccgroup/exploit_mitigations

2026-05-22 02:57 UTC
Security Update Guide - Microsoft

web:portal.msrc.microsoft.com

The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.

2026-05-22 02:57 UTC
Google Translate

web:translate.google.com

Google's service, offered free of charge, instantly translates words, phrases, and web pages between English and over 100 other languages.

2026-05-22 02:57 UTC
The August Patch Tuesday updates for Windows 11 are here, and they fix ...

web:windowsreport.com

It's that time of the month again: Microsoft has rolled out its Patch Tuesday updates for Windows 11 versions 23H2, 22H2, and 21H2. Windows 11 23H2 and 22H2 users will see their systems updated through KB5041585, while those on 21H2 will receive KB5041592. Post-update, your build versions will be 22621.4037, 22631.4037, and 22000.3147, respectively. The updates include quality improvements ...

2026-05-22 02:57 UTC
Microsoft confirms patching issues in restricted Windows networks

web:www.bleepingcomputer.com

Microsoft says customers in restricted network environments may encounter Windows Update failures after installing the January 2026 optional non-security preview updates.

2026-05-22 02:57 UTC
Resolving Sweet32, Birthday Attacks on Windows Servers Via GPO

web:www.experts-exchange.com

Learn more about Resolving Sweet32, Birthday Attacks on Windows Servers Via GPO from the expert community at Experts Exchange

2026-05-22 02:57 UTC
Microsoft provides mitigation for "YellowKey" BitLocker bypass flaw ...

web:www.helpnetsecurity.com

Microsoft is working on a fix for CVE -2026-45585 (aka "Yellowkey"), a vulnerability that can be used to bypass Windows' BitLocker protection.

2026-05-22 02:57 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2023-48238.json.

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