Jsonwebtoken
CVE-2026-25537
HIGH
GHSA-h395-gr6q-cpjc
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessCraft JWT with string-type nbf/exp claim
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DeliveryParser marks claim FailedToParse
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ExploitValidation treats as NotPresent
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ExecutionBypass expiration check
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ImpactAccess protected resource
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Type safety enforcement
MITRE ATT&CK
1 technique across 1 tactic: Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | jsonwebtoken library versions before 10.3.0 with validation enabled (validate_nbf=true or validate_exp=true) but claim not in required_spec_claims. No special configuration beyond standard JWT validation settings required. |
| Impact | CVSS 7.5 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: None. User interaction: None. Public exploit/POC available. |
| Exploit ScenarioDerived | An attacker could exploit this vulnerability to bypass critical time-based security restrictions (like “Not Before” checks) and. |
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Alert meAnalysisAIv1 – Mar 12, 2026
jsonwebtoken prior to version 10.3.0 allows attackers to bypass JWT time-based validation checks through type confusion when standard claims like nbf or exp are provided with incorrect JSON types. The library incorrectly treats malformed claims as absent rather than invalid, enabling bypass of critical security restrictions if validation is enabled but the claim is not explicitly marked as required. Public exploit code exists for this vulnerability.
Earlier versions of this analysis (1)
Jsonwebtoken versions up to 10.3.0 is affected by access of resource using incompatible type (type confusion) (CVSS 7.5).
RemediationAI
A vendor patch is available — apply it immediately. Fixed in version 10.3.0.. Restrict network access to the affected service where possible.
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in cargo
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
This vulnerability (CWE-843: Access of Resource Using Incompatible Type (Type Confusion)) affects Jsonwebtoken. jsonwebtoken is a JWT lib in rust. Prior to version 10.3.0, there is a Type Confusion vulnerability in jsonwebtoken, specifically, in its claim validation logic. When a standard claim (such as nbf or exp) is provided with an incorrect JSON type (Like a String instead of a Number), the library’s internal parsing mechanism marks the claim as “FailedToParse”. Crucially, the validation logic treats this “FailedToParse” state identically to “NotPresent”. This means that if a check is enabled (like: v
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Primary rating from GitHub Advisory.
CVSS VectorGitHub Advisory
Lifecycle Timeline
3DescriptionGitHub Advisory
jsonwebtoken is a JWT lib in rust. Prior to version 10.3.0, there is a Type Confusion vulnerability in jsonwebtoken, specifically, in its claim validation logic. When a standard claim (such as nbf or exp) is provided with an incorrect JSON type (Like a String instead of a Number), the library’s internal parsing mechanism marks the claim as “FailedToParse”. Crucially, the validation logic treats this “FailedToParse” state identically to “NotPresent”. This means that if a check is enabled (like: validate_nbf = true), but the claim is not explicitly marked as required in required_spec_claims, the library will skip the validation check entirely for the malformed claim, treating it as if it were not there. This allows attackers to bypass critical time-based security restrictions (like “Not Before” checks) and commit potential authentication and authorization bypasses. This issue has been patched in version 10.3.0.
Executive ViewAI
A type confusion vulnerability in the jsonwebtoken Rust library could allow attackers to bypass critical security validations (such as token expiration or not-before checks) by submitting malformed JWT claims. Organizations using affected versions of this library in authentication or authorization systems face potential unauthorized access risks.
Apply vendor patch. If immediate patching is not possible: implement strict input validation at the application layer to reject JWTs with non-numeric standard claims (nbf, exp, iat); enable WAF rules to detect and block malformed JWT payloads; monitor authentication logs for unusual claim validation failures; consider network segmentation to limit lateral movement from compromised tokens.
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.
Affected Products (CPE)GitHub Advisory
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