joserfc: Unbounded JWE General JSON recipients Array Leads to CPU Exhaustion (DoS) via Repeated RSA Private-Key Decryption

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-119283: 0.23% estimated exploitation activity in the next 30 days; percentile 13.75 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary `joserfc.jwe.decrypt_json()`, the library's public parser for JWE General JSON Serialization, accepts an attacker-controlled `recipients` array of unbounded length and performs one full private-key decryption operation (`decrypt_cek`) for every recipient present in the input, with no cap on recipient count. An unauthenticated network attacker who can send a JWE General JSON document to any endpoint that decrypts it with an RSA key (e.g. RSA-OAEP) can force the victim to perform an arbitrary, attacker-chosen number of RSA private-key decryption operations from a single, relatively small HTTP request. This gives the attacker a highly asymmetric CPU-exhaustion (Denial of Service) primitive: local reproduction shows request size growing linearly with recipient count (~396 bytes/recipient) while server-side CPU time grows in lock-step (near 1:1 ratio between recipient-count growth and decrypt-time growth), and the library's only documented mitigation knob,…

Published by the source

30 Oct 2026, 14:54 UTC

Last modified by the source

30 Oct 2026, 15:15 UTC

Source last checked

31 Oct 2026, 06:15 UTC

1. Revision 2 · amended · 31 Oct 2026

   Amended from osv record GHSA-jpxq-7h8p-2q76

2. Revision 1 · created · 30 Oct 2026

   Published from ghsa record GHSA-jpxq-7h8p-2q76

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-119283

Advisory: joserfc: Unbounded JWE General JSON `recipients` Array Leads to CPU Exhaustion (DoS) via Repeated RSA Private-Key Decryption
IDs: CVE-2026-119283, GHSA-jpxq-7h8p-2q76
Record: https://patchnext.com/advisories/cve-2026-119283 (revision 2, source checked 31 Oct 2026, 06:15 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: joserfc 1.7.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI joserfc: affected < 1.7.5; fixed in 1.7.5

## Suggested inspection (read-only)
- `python -m pip show joserfc`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on joserfc.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-jpxq-7h8p-2q76 (GitHub-reviewed advisory GHSA-jpxq-7h8p-2q76 lists affected ranges: PyPI joserfc >=0 <1.7.5)
- Verified: https://osv.dev/vulnerability/GHSA-jpxq-7h8p-2q76 (OSV record GHSA-jpxq-7h8p-2q76 lists affected ranges: PyPI joserfc >=0 <1.7.5 (fixed))

Commands are suggestions: review each one before running it.