CVE-2026-47121
Sparkle: Binary delta apply intermediate-symlink traversal in malicious .delta
Description
Sparkle is a software update framework for macOS. Prior to version 2.9.2, `Autoupdate/SUBinaryDeltaApply.m` enforces `relativePath.pathComponents containsObject:@".."` and rejects writes whose immediate parent directory IS itself a symbolic link, but does not detect symlinks deeper in the relative path. `Autoupdate/SPUSparkleDeltaArchive.m`'s `extractItem:` will create symlinks in the destination tree from archive content (no `..` check on the symlink target), and a subsequent `Extract` item targeting `<symlink>/foo/bar` then escapes the destination tree via `fopen(path, "wb")` because the kernel resolves the intermediate symlink during the open call. This is a defense-in-depth issue: exploitation requires a maliciously-crafted `.delta` that passes EdDSA signature verification, i.e. EdDSA private-key compromise. With the AppInstaller running as root for system-domain installs, it gives the holder of a stolen signing key arbitrary file write at root level via the delta-apply path, which is a strictly broader primitive than the "drop-in replacement bundle" install they would otherwise have. Version 2.9.2 contains a patch for the issue.
INFO
Published Date :
July 21, 2026, 2:16 p.m.
Last Modified :
July 21, 2026, 2:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | MEDIUM | MITRE-CVE |
Solution
- Update Sparkle to version 2.9.2 or later.
- Apply vendor patches for Sparkle.
- Ensure archive extraction validates symlink targets.
- Verify integrity of update archives.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-47121.
| URL | Resource |
|---|---|
| https://github.com/sparkle-project/Sparkle/commit/fe7b718d0736f3e139e374e26fbca96f29e13bf0 | |
| https://github.com/sparkle-project/Sparkle/security/advisories/GHSA-hg88-v3cw-3qrh |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-47121 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-47121
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-47121 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-47121 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Jul. 21, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'sparkle-project', 'product': 'Sparkle', 'versions': [{'status': 'affected', 'version': '< 2.9.2'}]}] Added Description Sparkle is a software update framework for macOS. Prior to version 2.9.2, `Autoupdate/SUBinaryDeltaApply.m` enforces `relativePath.pathComponents containsObject:@".."` and rejects writes whose immediate parent directory IS itself a symbolic link, but does not detect symlinks deeper in the relative path. `Autoupdate/SPUSparkleDeltaArchive.m`'s `extractItem:` will create symlinks in the destination tree from archive content (no `..` check on the symlink target), and a subsequent `Extract` item targeting `<symlink>/foo/bar` then escapes the destination tree via `fopen(path, "wb")` because the kernel resolves the intermediate symlink during the open call. This is a defense-in-depth issue: exploitation requires a maliciously-crafted `.delta` that passes EdDSA signature verification, i.e. EdDSA private-key compromise. With the AppInstaller running as root for system-domain installs, it gives the holder of a stolen signing key arbitrary file write at root level via the delta-apply path, which is a strictly broader primitive than the "drop-in replacement bundle" install they would otherwise have. Version 2.9.2 contains a patch for the issue. Added CVSS V3.1 AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N Added CWE CWE-22 Added CWE CWE-59 Added Reference https://github.com/sparkle-project/Sparkle/commit/fe7b718d0736f3e139e374e26fbca96f29e13bf0 Added Reference https://github.com/sparkle-project/Sparkle/security/advisories/GHSA-hg88-v3cw-3qrh