# CVE-2026-86983: Swift Crypto P-384 VOPRF denial of service via unbounded input length

Source: https://junglewise.ai/threats/cve-2026-86983-a-remote-attacker-may-be-able-to-terminate-a-process-that-passes  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-28. Updated: 2026-10-28  
License: CC BY 4.0 with a link back

CVE-2026-86983 · Severity: info · Published 2026-10-28

Swift Crypto's P-384 VOPRF API fails to enforce RFC 9497 input length limits, allowing a remote attacker to crash applications by passing inputs larger than 2^16 bytes. Applications that perform their own input validation or use fixed-size group elements are unaffected. The vulnerability can lead to denial of service in services that process user-supplied VOPRF inputs without proper bounds checking.

Technologies: [Apple Swift Crypto](https://junglewise.ai/threats/technologies/swift-crypto). Vendors: [Apple](https://junglewise.ai/threats/vendors/apple).

## Quick answers

**Is CVE-2026-86983 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-86983 being exploited in the wild.

**How severe is CVE-2026-86983?** Informational severity, published 28 October 2026.

**Which products and versions are affected?** Apple Swift Crypto 3.10.0 through 5.0.2.

**Is there a fix for CVE-2026-86983?** Yes: fixed in 5.0.3. Until then: Reject inputs of 2^16 bytes or more at your trust boundary before calling blind() or evaluate(); alternatively, hash longer inputs to a fixed length before passing them to the API, as specified in RFC 9497 §5.1. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-86983 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-86983?** Check whether you run Apple Swift Crypto at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 5.0.3

Reject inputs of 2^16 bytes or more at your trust boundary before calling blind() or evaluate(); alternatively, hash longer inputs to a fixed length before passing them to the API, as specified in RFC 9497 §5.1.

## Technical details

The P-384 VOPRF blind and evaluate APIs accept arbitrary-length input but fail to enforce the RFC 9497 two-byte length prefix limit of 2^16 - 1 bytes. When an oversized input is passed to blind() or evaluate(), the length encoding fails a precondition check, terminating the process. The vulnerability affects P384._VOPRF.PublicKey.blind(), finalize(), and P384._VOPRF.PrivateKey.evaluate() when called with attacker-controlled unbounded input; applications that validate input length beforehand or use evaluate() with fixed-size group elements are not affected.

## Affected products

- Apple Swift Crypto 3.10.0 through 5.0.2

## Timeline

- 2026-10-20: disclosed
- 2026-10-28: advisory

## References

- [https://github.com/apple/swift-crypto/security/advisories/GHSA-jwv7-rv4f-rff2](https://github.com/apple/swift-crypto/security/advisories/GHSA-jwv7-rv4f-rff2)

## Related threats

- [Apple swift-crypto double-free in RSA public key initialization](https://junglewise.ai/threats/cve-2026-43823-apple-swift-crypto-double-free-in-rsa-public-key-initialization)
- [Apple swift-crypto out-of-bounds read in X-Wing HPKE decapsulation](https://junglewise.ai/threats/cve-2026-28815-apple-swift-crypto-out-of-bounds-read-in-x-wing-hpke)