Red HatCVE-2026-85534
Red Hat libsoup.: reachable assertion
Medium5.9CVE-2026-85534 · Published Sep 4, 2026 · updated Sep 8, 2026
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.
Affected versions
| Package | Affected | Fixed in |
|---|---|---|
| Red Hat Enterprise Linux 10 Product | all versions | No fix yet |
| Red Hat Enterprise Linux 6 Product | all versions | No fix yet |
| Red Hat Enterprise Linux 7 Product | all versions | No fix yet |
| Red Hat Enterprise Linux 8 Product | all versions | No fix yet |
| Red Hat Enterprise Linux 9 Product | all versions | No fix yet |
Details and references
- CVSS 3.1
- CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- Severity from
- the vendor (its own CVE record or advisory)
- Weakness
- CWE-617
- www.cve.org/CVERecord?id=CVE-2026-85534
- nvd.nist.gov/vuln/detail/CVE-2026-85534
- access.redhat.com/security/cve/CVE-2026-85534
- bugzilla.redhat.com/show_bug.cgi?id=2528440
- gitlab.gnome.org/GNOME/libsoup/-/blob/master/libsoup/http2/soup-client-message-io-http2.c
- gitlab.gnome.org/GNOME/libsoup/-/work_items/551
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