How severe is CVE-2026-33204?

CVE-2026-33204 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-33204 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (38th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-33204?

CVE-2026-33204 affects Kelvinmo Simplejwt. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-33204?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-33204 have an EU (EUVD) identifier?

Yes. CVE-2026-33204 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-13871.

When was CVE-2026-33204 published?

CVE-2026-33204 was published on 2026-03-20 and last updated on 2026-06-17.

CVE-2026-33204

CVE-2026-33204 is a high-severity vulnerability in Kelvinmo Simplejwt with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-400.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (38th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-13871
Weakness: CWE-400
Affected product: Kelvinmo Simplejwt
Published: 2026-03-20
Last modified: 2026-06-17

Description

SimpleJWT is a simple JSON web token library written in PHP. Prior to version 1.1.1, an unauthenticated attacker can perform a Denial of Service via JWE header tampering when PBES2 algorithms are used. Applications that call JWE::decrypt() on attacker-controlled JWEs using PBES2 algorithms are affected. This issue has been patched in version 1.1.1.

Frequently asked questions

What is CVE-2026-33204?: SimpleJWT is a simple JSON web token library written in PHP. Prior to version 1.1.1, an unauthenticated attacker can perform a Denial of Service via JWE header tampering when PBES2 algorithms are used. Applications that call JWE::decrypt() on attacker-controlled JWEs using PBES2 algorithms are affected. This issue has been patched in version 1.1.1.
How severe is CVE-2026-33204?: CVE-2026-33204 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-33204 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (38th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-33204?: CVE-2026-33204 affects Kelvinmo Simplejwt. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-33204?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-33204 have an EU (EUVD) identifier?: Yes. CVE-2026-33204 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-13871.
When was CVE-2026-33204 published?: CVE-2026-33204 was published on 2026-03-20 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:kelvinmo:simplejwt:*:*:*:*:*:*:*:*

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