{"id":"CVE-2026-47121","summary":"Sparkle: Binary delta apply intermediate-symlink traversal in malicious .delta","details":"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 `\u003csymlink\u003e/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.","aliases":["GHSA-hg88-v3cw-3qrh"],"modified":"2026-07-25T03:56:29.612234896Z","published":"2026-07-21T13:53:05.030Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47121.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-22","CWE-59"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47121.json"},{"type":"ADVISORY","url":"https://github.com/sparkle-project/Sparkle/security/advisories/GHSA-hg88-v3cw-3qrh"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-47121"},{"type":"FIX","url":"https://github.com/sparkle-project/Sparkle/commit/fe7b718d0736f3e139e374e26fbca96f29e13bf0"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/sparkle-project/sparkle","events":[{"introduced":"0"},{"fixed":"fe7b718d0736f3e139e374e26fbca96f29e13bf0"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"2.9.2"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["2.9.1","2.9.0","2.9.0-beta.2","2.9.0-beta.1","2.8.0","2.8.0-beta.3","2.8.0-beta.2","2.8.0-beta.1","2.7.0","2.7.0-beta.1","2.6.2","2.6.1","2.6.0","2.6.0-beta.2","2.6.0-beta.1","2.5.1","2.5.0","2.5.0-beta.2","2.5.0-beta.1","2.4.2","2.4.1","2.4.1-beta.1","2.4.0","2.4.0-beta.2","2.4.0-beta.1","2.3.0","2.3.0-beta.2","2.3.0-beta.1","2.2.1","2.2.0","2.2.0-beta.2","2.2.0-beta.1","2.1.0","2.1.0-beta.2","2.1.0-beta.1","2.0.0","2.0.0-rc.1","2.0.0-beta.6","2.0.0-beta.5","2.0.0-beta.4","2.0.0-beta.3","2.0.0-beta.2","2.0.0-beta.1","1.14.0rc1","1.12.0","1.12.0a3","1.11.0rc2","1.11.0","1.12.0a2","1.12.0a1","1.11.0rc1","1.10.0rc1","1.10.0","1.9.0","1.9.0rc1","1.8.0","1.7.1","1.7.0","1.6.1","1.6.0","sparkle-1.5b6","sparkle-1.5b5","sparkle-1.5b4","sparkle-1.5b3","sparkle-1.5b2","sparkle-1.5b1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-47121.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N"}]}