What is CVE-2026-32253?

CVE-2026-32253 is a critical-severity vulnerability in Lizardbyte Sunshine, classified under Improper Authentication. CVSS score: 9.8/10. Published 2026-05-22.

How severe is CVE-2026-32253?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Auth bypass in Lizardbyte Sunshine

CVE-2026-32253

Sunshine is a self-hosted game stream host for Moonlight. In versions prior to 2026.516.143833, the client-certificate authentication can be bypassed because of how OpenSSL verification results are handled. In src/crypto.cpp, the custom verify callback treats X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY, X509_V_ERR_CERT_NOT_YET_VALID, and X509_V_ERR_CERT_HAS_EXPIRED as success. This can allow an untrusted certificate to pass authentication and access protected HTTPS endpoints. This issue has been fixed in version 2026.516.143833.

Vulnerability class: Broken Authentication

Published 2026-05-22 · last modified 2026-07-23.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.004 (35.9th percentile), scored 2026-10-20.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 36th percentile — 35.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001

Affected products

Lizardbyte Sunshine — versions < 2026.516.143833

Weakness classification (CWE)

References

github.com/LizardByte/Sunshine/security/advisories/GHSA-ph75-mgxh-mv57 (Exploit, Vendor Advisory)
github.com/LizardByte/Sunshine/releases/tag/v2026.516.143833 (Product, Release Notes)

Frequently asked questions

What is CVE-2026-32253?: CVE-2026-32253 is a critical-severity vulnerability in Lizardbyte Sunshine, classified under Improper Authentication. CVSS score: 9.8/10. Published 2026-05-22.
How severe is CVE-2026-32253?: Critical severity. CVSS v3 base score is 9.8 out of 10.