CVE-2026-47121 sparkle-project CVE debrief

Who should care

macOS users and administrators who utilize the Sparkle software update framework, particularly those with system-domain installs, should be aware of this vulnerability and take steps to update to version 2.9.2 or later. Affected operators, platforms, vulnerability-management, and security teams should review and act on this vulnerability.

Technical summary

The vulnerability exists in `Autoupdate/SUBinaryDeltaApply.m` and `Autoupdate/SPUSparkleDeltaArchive.m`. The `relativePath.pathComponents` check only rejects writes whose immediate parent directory is a symbolic link, but does not detect symlinks deeper in the relative path. The `extractItem:` method creates symlinks in the destination tree from archive content without a `..` check on the symlink target. A subsequent `Extract` item targeting `<symlink>/foo/bar` can escape the destination tree via `fopen(path, 'wb')`, allowing an attacker to write files at the root level.

Defensive priority

High

Recommended defensive actions

• Update Sparkle to version 2.9.2 or later
• Verify the integrity of the Sparkle installation and ensure the AppInstaller is not running with elevated privileges
• Monitor for suspicious activity and implement compensating controls to prevent exploitation
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
• Review compensating controls for exposed systems while remediation is scheduled and verified.

Evidence notes

The CVE record was published on 2026-07-21T14:16:34.387Z and was last modified on 2026-07-22T15:17:16.413Z. The NVD entry is currently MEDIUM. The Sparkle software update framework for macOS, prior to version 2.9.2, is vulnerable to an arbitrary file write issue due to a defense-in-depth vulnerability. This vulnerability allows an attacker with a compromised EdDSA private key to write files at the root level via the delta-apply path. The CVE record was published on 2026-07-21T14:16:34.387Z and has not been modified since then.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.