# CVE-2026-43823: Apple swift-crypto double-free in RSA public key initialization

Source: https://junglewise.ai/threats/cve-2026-43823-apple-swift-crypto-double-free-in-rsa-public-key-initialization  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-23. Updated: 2026-07-23  
License: CC BY 4.0 with a link back

CVE-2026-43823 · Severity: info · CVSS 9.8 · Published 2026-07-23

Apple's Swift Crypto library, which provides cryptographic functions for Swift applications, contains a memory management flaw. When an application attempts to process a malformed or invalid RSA public key, the library may crash or allow for unpredictable behavior due to a memory error. This could potentially be used by an attacker to disrupt services or gain unauthorized control over an application that processes public keys from untrusted sources.

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

## Quick answers

**Is CVE-2026-43823 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-43823 being exploited in the wild.

**How severe is CVE-2026-43823?** Informational severity, with a CVSS score of 9.8, published 23 July 2026.

**Which products and versions are affected?** Apple Swift Crypto >= 3.2.0, <= 4.5.0.

**Is there a fix for CVE-2026-43823?** A patch was published on 2026-07-23: Vulnerability addressed in version 4.5.1 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-43823 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-43823?** 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.

## Technical details

A double-free vulnerability exists in Apple's swift-crypto library when initializing RSA public keys. The flaw occurs when BoringSSL fails to decode a public key from provided DER or PEM bytes; the underlying EVP_PKEY* object is freed once in a catch block and subsequently freed again during deinitialization. This affects _RSA.Encryption.PublicKey, _RSA.Signing.PublicKey, and _RSA.BlindSigning.PublicKey. An attacker providing malformed key data to an application using these APIs can trigger a heap corruption, leading to a denial-of-service (crash) or potentially arbitrary code execution. The issue is resolved in version 4.5.1.

## Affected products

- Apple swift-crypto >= 3.2.0, <= 4.5.0

## Timeline

- 2026-07-16: advisory: GitHub Security Advisory published
- 2026-07-23: disclosed: NVD publication date
- 2026-07-23: patched: Vulnerability addressed in version 4.5.1

## References

- [https://github.com/apple/swift-crypto/security/advisories/GHSA-8q93-f6xh-4f6f](https://github.com/apple/swift-crypto/security/advisories/GHSA-8q93-f6xh-4f6f)

## Related threats

- [Swift Crypto P-384 VOPRF denial of service via unbounded input length](https://junglewise.ai/threats/cve-2026-86983-a-remote-attacker-may-be-able-to-terminate-a-process-that-passes)
- [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)