What is CVE-2022-34478?

CVE-2022-34478 is a medium-severity vulnerability in Microsoft Windows, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 6.5/10. Published 2022-12-22.

How severe is CVE-2022-34478?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Is CVE-2022-34478 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Open Redirect in Microsoft Windows

CVE-2022-34478

The <code>ms-msdt</code>, <code>search</code>, and <code>search-ms</code> protocols deliver content to Microsoft applications, bypassing the browser, when a user accepts a prompt. These applications have had known vulnerabilities, exploited in the wild (although we know of none exploited through Thunderbird), so in this release Thunderbird has blocked these protocols from prompting the user to open them.<br>*This bug only affects Thunderbird on Windows. Other operating systems are unaffected.*. This vulnerability affects Firefox < 102, Firefox ESR < 91.11, Thunderbird < 102, and Thunderbird < 91.11.

Vulnerability class: Open Redirect

Published 2022-12-22 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.008 (54.3th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 54th percentile — 54.3% 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: 0.008 · change: 0.000

Affected products

Microsoft Windows
Mozilla Firefox — versions unspecified
Mozilla Firefox Esr — versions unspecified
Mozilla Firefox Esr
Mozilla Thunderbird — versions unspecified

Weakness classification (CWE)

CWE-601 — URL Redirection to Untrusted Site (Open Redirect)

Public proof-of-concept exploits

j00sean/CVE-2022-44666

References

www.mozilla.org/security/advisories/mfsa2022-24/ (Vendor Advisory)
www.mozilla.org/security/advisories/mfsa2022-26/ (Vendor Advisory)
www.mozilla.org/security/advisories/mfsa2022-25/ (Vendor Advisory)
bugzilla.mozilla.org/show_bug.cgi (Permissions Required, Issue Tracking, Vendor Advisory)

Frequently asked questions

What is CVE-2022-34478?: CVE-2022-34478 is a medium-severity vulnerability in Microsoft Windows, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 6.5/10. Published 2022-12-22.
How severe is CVE-2022-34478?: Medium severity. CVSS v3 base score is 6.5 out of 10.
Is CVE-2022-34478 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.