How severe is CVE-2026-48525?

CVE-2026-48525 has a CVSS 3.x base score of 5.3, rated medium 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 low.

Is CVE-2026-48525 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-48525?

CVE-2026-48525 affects Pyjwt Project Pyjwt. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-48525?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-48525 have an EU (EUVD) identifier?

Yes. CVE-2026-48525 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-32919.

When was CVE-2026-48525 published?

CVE-2026-48525 was published on 2026-05-28 and last updated on 2026-06-17.

CVE-2026-48525

CVE-2026-48525 is a medium-severity vulnerability in Pyjwt Project Pyjwt with a CVSS 3.x base score of 5.3. 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: Medium (CVSS 3.x base score 5.3)
EPSS exploit prediction: 0% (21st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-32919
Weakness: CWE-400
Affected product: Pyjwt Project Pyjwt
Published: 2026-05-28
Last modified: 2026-06-17

Description

PyJWT is a JSON Web Token implementation in Python. From 2.8.0 to 2.12.1, when verifying detached JWS tokens using the unencoded-payload option ("b64": false, RFC 7797), PyJWT performs Base64URL decoding of the compact-serialization payload segment before enforcing the detached-payload rules. For b64=false, PyJWT later discards that decoded payload and replaces it with the caller-provided detached_payload. In practice, this turns the middle segment into an attacker-controlled “work amplifier”: a remote client can supply an arbitrarily large Base64URL payload segment that forces CPU work + memory allocations even if the signature is invalid. This creates an unauthenticated DoS vector against any endpoint that verifies detached JWS using PyJWT. This vulnerability is fixed in 2.13.0.

Frequently asked questions

What is CVE-2026-48525?: PyJWT is a JSON Web Token implementation in Python. From 2.8.0 to 2.12.1, when verifying detached JWS tokens using the unencoded-payload option ("b64": false, RFC 7797), PyJWT performs Base64URL decoding of the compact-serialization payload segment before enforcing the detached-payload rules. For b64=false, PyJWT later discards that decoded payload and replaces it with the caller-provided detached_payload. In practice, this turns the middle segment into an attacker-controlled “work amplifier”: a remote client can supply an arbitrarily large Base64URL payload segment that forces CPU work + memory allocations even if the signature is invalid. This creates an unauthenticated DoS vector against any endpoint that verifies detached JWS using PyJWT. This vulnerability is fixed in 2.13.0.
How severe is CVE-2026-48525?: CVE-2026-48525 has a CVSS 3.x base score of 5.3, rated medium 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 low.
Is CVE-2026-48525 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-48525?: CVE-2026-48525 affects Pyjwt Project Pyjwt. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-48525?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-48525 have an EU (EUVD) identifier?: Yes. CVE-2026-48525 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-32919.
When was CVE-2026-48525 published?: CVE-2026-48525 was published on 2026-05-28 and last updated on 2026-06-17.

References

https://github.com/jpadilla/pyjwt/security/advisories/GHSA-w7vc-732c-9m39

Affected products (1)

cpe:2.3:a:pyjwt_project:pyjwt:*:*:*:*:*:*:*:*

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