CVE-2026-85534

A flaw was found in libsoup. When a client sends an HTTP/2 request body from a non-pollable input stream, the library can buffer more data than the current flow-control window later allows. A malicious HTTP/2 server can shrink SETTINGS_INITIAL_WINDOW_SIZE while that buffered read is still in progress. The client then copies the full buffer into a smaller DATA callback without a runtime bounds check, which can abort the process or fail the HTTP/2 session.

CVSS v3 5.9 MEDIUM

5.9^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.2 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://access.redhat.com/security/cve/CVE-2026-85534
https://bugzilla.redhat.com/show_bug.cgi?id=2528440
https://gitlab.gnome.org/GNOME/libsoup/-/blob/master/libsoup/http2/soup-client-message-io-http2.c
https://gitlab.gnome.org/GNOME/libsoup/-/work_items/551

Configurations

No configuration.

History

No history.

Information

Published : 2026-09-04 11:17

Updated : 2026-09-08 19:08

NVD link : CVE-2026-85534

Mitre link : CVE-2026-85534

CVE.ORG link : CVE-2026-85534

JSON object : View

Products Affected

No product.

CWE

CWE-617

Reachable Assertion

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