VulnerabilityAwaiting Analysis

CVE-2026-85534

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.

MEDIUM 5.9EPSS 0.32%

Does this matter?

Lower severity and a low EPSS score (0.32%). Track it; it rarely justifies an emergency change on its own.

Description

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 3.1: 5.9 MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS: 0.32% probability · 24th percentile
CISA KEV: Not listed
Weakness: CWE-617
Source: secalert@redhat.com

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.