# CVE-2026-48524: PyJWT: PyJWKClient unbounded JWKS endpoint requests via attacker-controlled kid values (DoS)

> Attackers can cause denial of service by forcing unlimited outbound requests to JWKS endpoints using unknown key IDs in JWT headers.

- **Severity:** Low 3.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 May 2026
- **Updated:** 28 May 2026
- **Also known as:** AZL-93027, BELL-CVE-2026-48524, CLEANSTART-2026-QN15883, DEBIAN-CVE-2026-48524, ECHO-5526-5e92-5565, GHSA-fhv5-28vv-h8m8, MINI-22v2-g977-h32v, MINI-3fv6-hvcx-cpcg, MINI-3gjv-c268-gc72, MINI-3j2c-hr5f-gvfq, MINI-4ppc-4338-3gp4, MINI-543h-hpj9-vh2j, MINI-5xqq-rm8r-64w8, MINI-623r-hgvx-gv3p, MINI-6564-785r-w84c, MINI-6g43-9hm6-xf94, MINI-6pc8-x8rj-3hv5, MINI-72v6-c866-q6ch, MINI-7q62-h829-2fp7, MINI-8922-mmrr-hh46, MINI-992f-9634-99wq, MINI-9xrh-hq5w-55m4, MINI-c9x3-4fvv-4c25, MINI-cghx-q6cf-4cgf, MINI-fmc7-8qww-cqcg, MINI-h479-6wg2-8rpm, MINI-hvj3-8v3g-3cwc, MINI-jwpg-px7j-685q, MINI-rhjh-5pf8-4vp4, MINI-vh9h-j9jj-hxw5, MINI-wp6j-p7gc-7f4m, MINI-wqg3-g3rr-vmmm, MINI-x5mc-rcp8-75c4, MINI-x78x-q7vm-32jm, PYSEC-2026-177, ROOT-APP-PYPI-CVE-2026-48524, UBUNTU-CVE-2026-48524

## What is CVE-2026-48524?

CVE-2026-48524 is a low-severity denial of service vulnerability in jpadilla pyjwt, published on 28 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

PyJWT is a JSON Web Token implementation in Python. Prior to 2.13.0, PyJWKClient.get_signing_key() forces a fresh HTTP request to the JWKS endpoint for every JWT with an unknown kid value, with no rate limiting. Since kid comes from the unverified token header, an attacker can trigger unlimited outbound requests. The vulnerability surfaces only when a JWKS fetch fails; an attacker can attempt to provoke that with sustained unknown-kid traffic, but the outcome depends on upstream JWKS-endpoint behavior (rate limiting, transient errors) which is beyond the attacker's control. This vulnerability is fixed in 2.13.0.

Weakness: CWE-755 (Improper Handling of Exceptional Conditions), CWE-460 (Improper Cleanup on Thrown Exception)

## Which versions are affected by CVE-2026-48524?

3 open source packages ship an affected version, including pyjwt. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `pyjwt` | PyPI | All versions | 2.13.0 |
| `pyjwt` | PyPI | From 2.0.0 | 2.13.0 |
| `pyjwt` | PyPI | From 2.0.0 | 2.13.0 |

Products: Pyjwt Project Pyjwt.

## How do I fix CVE-2026-48524?

Upgrade pyjwt to 2.13.0 or later.

## Is CVE-2026-48524 being exploited?

There is no known exploitation of CVE-2026-48524 in the wild and no public exploit code.

## Other vulnerabilities in jpadilla pyjwt

- [CVE-2026-102268](https://insights.sbomify.com/CVE-2026-102268/): PyJWT: Asymmetric-PEM detection bypass: whitespace/line-ending-mutated public keys skip the HS/asymmetric confusion guard (critical 9.1)
- [CVE-2026-32597](https://insights.sbomify.com/CVE-2026-32597/): PyJWT accepts unknown `crit` header extensions (RFC 7515 §4.1.11 MUST violation) (high 7.5)
- [CVE-2026-102266](https://insights.sbomify.com/CVE-2026-102266/): PyJWK accepts empty HMAC keys, bypassing PyJWT's empty-key validation (high 7.4)
- [CVE-2026-102267](https://insights.sbomify.com/CVE-2026-102267/): PyJWT: PyJWKClient follows redirects when fetching JWKS (high 7.4)
- [CVE-2026-102271](https://insights.sbomify.com/CVE-2026-102271/): PyJWT: Public keys in DER form are accepted as HMAC secrets, bypassing the CVE-2022-29217 guard (high 7.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-48524 and fix it if it is affected.

What it is: CVE-2026-48524 is a low-severity denial of service vulnerability in jpadilla pyjwt, published on 28 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-48524 in the wild and no public exploit code.

Affected packages and fixed versions:
- pyjwt (PyPI): affected all versions; fixed in 2.13.0
- pyjwt (PyPI): affected from 2.0.0; fixed in 2.13.0
- pyjwt (PyPI): affected from 2.0.0; fixed in 2.13.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-48524/ (Markdown: https://insights.sbomify.com/CVE-2026-48524/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-48524
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-48524
- OSV: https://osv.dev/vulnerability/CVE-2026-48524

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-48524/
Summaries are generated and may contain mistakes; the official description above is the record.