What is CVE-2026-33819?

CVE-2026-33819 is a critical-severity vulnerability in Microsoft Bing, classified under Deserialization of Untrusted Data. CVSS score: 10.0/10. Published 2026-04-23.

How severe is CVE-2026-33819?

Critical severity. CVSS v3 base score is 10.0 out of 10.

Deserialization in Microsoft Bing

CVE-2026-33819

Deserialization of untrusted data in Microsoft Bing allows an unauthorized attacker to execute code over a network.

Vulnerability class: Insecure Deserialization

Published 2026-04-23 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.015 (73.8th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 74th percentile — 73.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.015 · change: +0.007

Affected products

Weakness classification (CWE)

CWE-502 — Deserialization of Untrusted Data

References

Microsoft Bing Remote Code Execution Vulnerability (vendor-advisory, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-33819?: CVE-2026-33819 is a critical-severity vulnerability in Microsoft Bing, classified under Deserialization of Untrusted Data. CVSS score: 10.0/10. Published 2026-04-23.
How severe is CVE-2026-33819?: Critical severity. CVSS v3 base score is 10.0 out of 10.