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CVE Record

CVE-2026-32597: PyJWT accepts unknown `crit` header extensions (RFC 7515 §4.1.11 MUST violation)

PyJWT is a JSON Web Token implementation in Python. Prior to 2.12.0, PyJWT does not validate the crit (Critical) Header Parameter defined in RFC 7515 §4.1.11. When a JWS token contains a crit array listing extensions that PyJWT does not understand, the library accepts the token instead of rejecting it. This violates the MUST requirement in the RFC. This vulnerability is fixed in 2.12.0.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

PyJWT before 2.12.0 may accept signed tokens that say they require critical handling the library does not understand. In authentication or authorization paths, that can let token integrity assumptions become wrong. The public bundle says the flaw is fixed in 2.12.0 and rates it high severity.

Executive priority

Treat as high priority for systems that depend on JWTs for access control. Patch promptly, starting with public APIs and identity-facing services. The evidence supports integrity risk, but not confirmed active exploitation.

Technical view

PyJWT fails to enforce RFC 7515 section 4.1.11 for the JWS crit header. Tokens containing unknown critical header extensions are accepted instead of rejected. CVSS 3.1 is 7.5, with network attack vector, low complexity, no privileges, no user interaction, and high integrity impact.

Likely exposure

Exposure is likely in Python applications or packaged products that use PyJWT versions below 2.12.0 to validate JWT or JWS input, especially authentication, authorization, session, API, and identity integrations.

Exploitation context

The bundle does not show CISA KEV listing or active exploitation. CVSS indicates remote unauthenticated reachability where vulnerable token validation is exposed. Actual exploitability depends on how the application interprets critical token extensions and authorization decisions.

Researcher notes

The key issue is standards noncompliance: unknown crit extensions must cause rejection. Assess whether applications rely on extension semantics, custom token profiles, or cross-library verification behavior. Do not assume all PyJWT usage is equally exposed.

Mitigation direction

  • Upgrade PyJWT to version 2.12.0 or later.
  • Apply fixed vendor packages from Debian, Red Hat, or other applicable distributions.
  • Prioritize internet-facing authentication and API token validation services.
  • Review vendor advisories for product-specific remediation status.
  • Avoid accepting untrusted JWT/JWS tokens through vulnerable validation paths.

Validation and detection

  • Inventory PyJWT versions in dependency files, SBOMs, containers, and deployed environments.
  • Confirm runtime environments no longer load PyJWT below 2.12.0.
  • Verify token validators reject unsupported critical JWS headers.
  • Check Red Hat and Debian advisories for distribution package status.
  • Review authentication logs for unusual token validation failures after patching.
Prepared
Confidence
high
Sources
8

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-345: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cwe · low confidence lookup

CWE-347: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cwe · medium confidence lookup

CWE-863: Authorization and privilege behavior lookup

Authorization weaknesses can support privilege escalation and valid-account review, depending on exploit path. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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description · low confidence lookup

Credential and access behavior lookup

The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-32597 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
3ADP providers
35Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: pocAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N3.93.6GitHub_M
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-32597Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container
redhat-SADPpyjwt: PyJWT accepts unknown `crit` header extensions (RFC 7515 §4.1.11 MUST violation)
other:Red Hat severity ratingcvssV3_1
  • 2026-03-12T22:01:29.967Z: Reported to Red Hat.
  • 2026-03-12T21:41:50.427Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
jpadillapyjwt< 2.12.0Listed
Weakness

CWE details

CWE-345CWE-347CWE-863

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-345 · source CWE mapping

Insufficient Verification of Data Authenticity

Insufficient Verification of Data Authenticity represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-347 · source CWE mapping

Improper Verification of Cryptographic Signature

Improper Verification of Cryptographic Signature represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-863 · source CWE mapping

Incorrect Authorization

Incorrect Authorization represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs