What is CVE-2026-103399?

CVE-2026-103399 is a security advisory published by Microsoft Security Response Center (MSRC) with Medium severity. Libsoup: soupserver: http/1 request smuggling via undrained expect: 100-continue body

Which CVE IDs does CVE-2026-103399 cover?

CVE-2026-103399 covers the following CVE IDs: CVE-2026-103399. Each CVE has its own detail page on EchelonGraph Pulse with the synthesized EG score.

What is the CVSS v3 score of CVE-2026-103399?

CVE-2026-103399 has a CVSS v3 base score of 5.3, published by Microsoft Security Response Center (MSRC).

Which products are affected by CVE-2026-103399?

CVE-2026-103399 affects 1 product, including: azl3 libsoup 3.4.4-16 on Azure Linux 3.0.

CVE-2026-103399MediumCVSS 5.3

Libsoup: soupserver: http/1 request smuggling via undrained expect: 100-continue body

Vendor

Microsoft Security Response Center (MSRC)

Published

October 3, 2026

Last Modified

—

🔗 CVE IDs covered (1)

CVE-2026-103399 →

🎯 Affected products1

azl3 libsoup 3.4.4-16 on Azure Linux 3.0

✅ Remediation

KBRelease Notes (Security Update)

🔗 References (2)

advisoryhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-103399
referencehttps://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade