Sparkle: Binary delta apply intermediate-symlink traversal in malicious .delta

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-47121
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-21 14:16:34 UTC
Updated2026-07-22 15:17:16 UTC
DescriptionSparkle 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.

Risk And Classification

Primary CVSS: v3.1 6.1 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N

EPSS: 0.002290000 probability, percentile 0.137770000 (date 2026-07-22)

Problem Types: CWE-22 | CWE-59 | CWE-22 CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') | CWE-59 CWE-59: Improper Link Resolution Before File Access ('Link Following')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.1MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N
3.1CNADECLARED6.1MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Sparkle-project Sparkle affected < 2.9.2 Not specified

References

ReferenceSourceLinkTags
github.com/sparkle-project/Sparkle/security/advisories/GHSA-hg88-v3cw-3qrh 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/sparkle-project/Sparkle/commit/fe7b718d0736f3e139e374e26fbca9... [email protected] github.com
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