Sparkle's AppInstaller post-stage-1 XPC listener accepts unvalidated connections, allowing spoofed appcast item data injection

published 2026-05-29 5 mo ago modified 2026-10-24 15 d ago also EUVD-2026-46275 , GHSA-g3hp-f6mg-559v

cvss: 4.2; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.1%; EPSS 0.1% chance of exploitation in 30 days, percentile 1%
public exploits: 0; none known

Sparkle is a software update framework for macOS. In versions up to and including 2.9.1, `Autoupdate/AppInstaller.m`'s `shouldAcceptNewConnection:` only enforces `SUCodeSigningVerifier validateConnection:` before stage 1 completes. After `_performedStage1Installation = YES`, new connections to the registered Mach service `<bundleId>-spki` are accepted from any local process without team-ID or code-signing checks. As of time of publication, no known patched versions are available.

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 3 mo ago (2026-07-21)

Exploit prediction

0.10% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	4.2	CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:L
GitHub	3.1	4.2	CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:L

Affected packages

ecosystem	package	affected	fixed in
swift	github.com/sparkle-project/Sparkle	<=2.9.1	no fix listed

Affected products

sparkle-project Sparkle

Classification

Weakness

CWE-306 Missing Authentication for Critical Functionality
CWE-441 Unintended Proxy or Intermediary

References

github.com /sparkle-project/Sparkle/security/advisories/GHSA-g3hp-f6mg-559v
web, vendor-advisory, mitigation
github.com /sparkle-project/Sparkle
package

Sources

Fencer Vulns 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.

Summary