Summary
PyJWT: PyJWKClient follows redirects when fetching JWKS
PyJWT 2.13.0 PyJWKClient followed HTTP redirects while fetching a JWKS,
without validating the redirect destination. A configured trusted endpoint
could therefore redirect the client to a different host.
Affected versions
PyJWT <= 2.13.0.
Credit
Credit: the original reporter of GHSA-9v7f-9g4p-ffgj. Additional redirect
header-leak and cache-poisoning evidence from the newer duplicate report
GHSA-43g3-98cx-x446 is preserved in the duplicate record and informed this
canonical advisory update.
Maintainer update, 2026-09-11
The verified fix for this advisory is included in PyJWT 2.14.0, released on 2026-09-11 and available on PyPI. PyJWT 2.14.0 is the first release containing the fix. This advisory is now published with 2.14.0 recorded as the patched version.
Impact
When an application uses PyJWKClient with caller-supplied request headers and
an attacker can influence the configured endpoint's response, the redirected
request could expose those headers and the redirected response could be used as
authoritative key material. This could cause JWKS trust poisoning and, in
affected mixed-configuration applications, forged JWT acceptance. The issue
requires an attacker-influenced redirect from the configured JWKS endpoint; it
is not triggered by a token kid alone.
Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.
CVE-2026-102267 has a CVSS score of 7.4 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.14.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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The issue is fixed on master in commit0a795b8e1f6ef08f634aa7086fc41cc6d5ce3e56.PyJWKClient now disables automatic redirects for JWKS fetches. Regression
tests verify that a redirect is rejected without contacting its destination,
while normal fetches, headers, caching, errors, timeouts, and SSL context remain
covered.
The fix is present in the unreleased development branch. The patched version
will be recorded after a released PyJWT 2.x version containing the fix is
confirmed.
Frequently Asked Questions
- What is CVE-2026-102267? CVE-2026-102267 is a high-severity server-side request forgery (SSRF) vulnerability in PyJWT (pip), affecting versions <= 2.13.0. It is fixed in 2.14.0. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
- How severe is CVE-2026-102267? CVE-2026-102267 has a CVSS score of 7.4 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of PyJWT are affected by CVE-2026-102267? PyJWT (pip) versions <= 2.13.0 is affected.
- Is there a fix for CVE-2026-102267? Yes. CVE-2026-102267 is fixed in 2.14.0. Upgrade to this version or later.
- Is CVE-2026-102267 exploitable, and should I be worried? Whether CVE-2026-102267 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-102267 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-102267? Upgrade
PyJWTto 2.14.0 or later.