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Fencer Intel
medium 6.1

CVE-2026-47121 json

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

published 5mo ago modified 17d ago also EUVD-2026-46259 , GHSA-hg88-v3cw-3qrh

cvss
6.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 27%
public exploits
0
none known

Summary

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.

Patch / fix

  • swift github.com/sparkle-project/Sparkle 2.9.2
  • sparkle-project sparkle 2.9.2

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
3mo ago

Exploit prediction

0.34% chance of exploitation in the next 30 days, higher than 27% of all scored CVEs (FIRST EPSS, 2026-11-10).

Exploits and checks

  • github.com https://github.com/sparkle-project/Sparkle/security/advisories/GHSA-hg88-v3cw-3qrh referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N
GitHub 3.1 6.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
swift github.com/sparkle-project/Sparkle
<2.9.2
2.9.2

Affected products

  • sparkle-project Sparkle

Classification

Weakness
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory
  • CWE-59 Improper Link Resolution Before File Access

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.