# CVE-2026-47121: Sparkle path traversal via intermediate symlinks in delta updates

Source: https://junglewise.ai/threats/cve-2026-47121-sparkle-path-traversal-via-intermediate-symlinks-in-delta-updates  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-21. Updated: 2026-07-21  
License: CC BY 4.0 with a link back

CVE-2026-47121 · Severity: medium · CVSS 6.1 · Published 2026-07-21

Sparkle is a widely used software update framework for macOS applications. A vulnerability in how it handles update files could allow an attacker who has compromised a developer's signing key to write files anywhere on a user's system, including protected system directories if the installer is running with administrative privileges. While this requires a stolen signing key to execute, it allows for a much deeper level of system compromise than a standard malicious update would normally permit.

Vendors: [Swift](https://junglewise.ai/threats/vendors/swift).

## Quick answers

**Is CVE-2026-47121 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-47121 being exploited in the wild.

**How severe is CVE-2026-47121?** Medium severity, with a CVSS score of 6.1, published 21 July 2026.

**Which products and versions are affected?** Sparkle Project Sparkle < 2.9.2, <= 2.9.1; github.com/sparkle-project/Sparkle (Swift) <= 2.9.1.

**Is there a fix for CVE-2026-47121?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-47121 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-47121?** Check whether you run Sparkle Project Sparkle or github.com/sparkle-project/Sparkle (Swift) 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 path traversal vulnerability exists in Sparkle's `SUBinaryDeltaApply.m` and `SPUSparkleDeltaArchive.m` components. The framework's delta update mechanism fails to recursively validate all path components for symbolic links. An attacker can craft a `.delta` archive that first creates a symlink pointing to a sensitive system directory (e.g., `/Library/LaunchDaemons`) and then extracts a subsequent file using a path that traverses through that symlink. Because `fopen()` resolves intermediate symlinks, the file is written outside the intended destination tree. Exploitation requires the attacker to possess a valid EdDSA signing key to pass signature verification. If the update process is running as root (system-domain installs), this grants arbitrary root-level file write capabilities. The issue is addressed in version 2.9.2.

## Affected products

- sparkle-project Sparkle < 2.9.2

## Identifiers

- CVE-2026-47121
- GHSA-hg88-v3cw-3qrh

## Timeline

- 2026-05-19: advisory: Internal GitHub advisory published
- 2026-07-21: disclosed: NVD publication date

## References

- [https://github.com/sparkle-project/Sparkle/commit/fe7b718d0736f3e139e374e26fbca96f29e13bf0](https://github.com/sparkle-project/Sparkle/commit/fe7b718d0736f3e139e374e26fbca96f29e13bf0)
- [https://github.com/sparkle-project/Sparkle/security/advisories/GHSA-hg88-v3cw-3qrh](https://github.com/sparkle-project/Sparkle/security/advisories/GHSA-hg88-v3cw-3qrh)

## Related threats

- [Sparkle missing authentication in AppInstaller Mach service connection](https://junglewise.ai/threats/cve-2026-47122-sparkle-missing-authentication-in-appinstaller-mach-service)