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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 | — | — |
| Red Hat | Red Hat Enterprise Linux 6 | — | — |
| Red Hat | Red Hat Enterprise Linux 7 | — | — |
| Red Hat | Red Hat Enterprise Linux 8 | — | — |
| Red Hat | Red Hat Enterprise Linux 9 | — | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 13 | libsoup3 | No fix yet | — |
| Debian 12 | libsoup3 | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | libsoup3 | 3.6.6-1ubuntu3 | USN-8890-2 |
| Ubuntu 26.04 LTS | libsoup3 | 3.6.6-1ubuntu0.1 | USN-8890-1 |
| Ubuntu 24.04 LTS | libsoup2.4 | 2.74.3-6ubuntu1.9 | USN-8890-1 |
| Ubuntu 24.04 LTS | libsoup3 | 3.4.4-5ubuntu0.9 | USN-8890-1 |
| Ubuntu 22.04 LTS | libsoup2.4 | 2.74.2-3ubuntu0.9 | USN-8890-1 |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 26.04 LTS | libsoup2.4 | 2.74.3-10.1ubuntu5+esm3 | USN-8890-1 |
| Ubuntu Pro 22.04 LTS | libsoup3 | 3.0.7-0ubuntu1+esm9 | USN-8890-1 |
| Ubuntu Pro 20.04 LTS | libsoup2.4 | 2.70.0-1ubuntu0.5+esm4 | USN-8890-1 |
| Ubuntu Pro 18.04 LTS | libsoup2.4 | 2.62.1-1ubuntu0.4+esm9 | USN-8890-1 |
| Ubuntu Pro 16.04 LTS | libsoup2.4 | 2.52.2-1ubuntu0.3+esm8 | USN-8890-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | libsoup | 3.4.4-150600.3.53.1 | SUSE-SU-2026:4273-1 |
| SLES 15 SP6 | libsoup | 3.4.4-150600.3.53.1 | SUSE-SU-2026:4273-1 |
| SLES 15 SP5 | libsoup | 3.0.4-150400.3.49.1 | SUSE-SU-2026:4274-1 |
| SLES 15 SP4 | libsoup | 3.0.4-150400.3.49.1 | SUSE-SU-2026:4274-1 |
Show 10 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | libsoup | 3.6.6-160000.4.1 | SUSE-SU-2026:23866-1, SUSE-SU-2026:23857-1 |
| SLES for SAP 15 SP6 | libsoup | 3.4.4-150600.3.53.1 | SUSE-SU-2026:4273-1 |
| SLES for SAP 15 SP5 | libsoup | 3.0.4-150400.3.49.1 | SUSE-SU-2026:4274-1 |
| SLES for SAP 15 SP4 | libsoup | 3.0.4-150400.3.49.1 | SUSE-SU-2026:4274-1 |
| SLES 16.0 | libsoup | 3.6.6-160000.4.1 | SUSE-SU-2026:23866-1, SUSE-SU-2026:23857-1 |
| SLE Micro 6.2 | libsoup | 3.6.6-160000.4.1 | SUSE-SU-2026:23848-1 |
| SLE Micro 6.1 | libsoup | 3.4.4-slfo.1.1_11.1 | SUSE-SU-2026:23923-1 |
| SLE Micro 6.0 | libsoup | 3.4.2-18.1 | SUSE-SU-2026:23875-1 |
| SLE HPC 15 SP5 | libsoup | 3.0.4-150400.3.49.1 | SUSE-SU-2026:4274-1 |
| SLE HPC 15 SP4 | libsoup | 3.0.4-150400.3.49.1 | SUSE-SU-2026:4274-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | libsoup | 3.6.6-9.1 | openSUSE-SU-2026:11823-1 |
| openSUSE Leap 16.0 | libsoup | 3.6.6-160000.4.1 | openSUSE-SU-2026:21901-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | libsoup3 +2 | 3.7.2-1.amzn2023 | ALAS2023-2026-3144 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | libsoup | No fix yet | — |
Advisories 12
- USN-8890-2 libsoup3 vulnerabilities Ubuntu Security Notices (USN) · Oct 22, 2026
- USN-8890-1 libsoup2.4, libsoup3 vulnerabilities Ubuntu Security Notices (USN) · Oct 7, 2026
- SUSE-SU-2026:23923-1 Security update for libsoup SUSE / openSUSE Security Updates · Sep 30, 2026
- ALAS2023-2026-3144 Important: libsoup3 security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Sep 28, 2026
- SUSE-SU-2026:23875-1 Security update for libsoup SUSE / openSUSE Security Updates · Sep 28, 2026
- SUSE-SU-2026:23857-1 Security update for libsoup SUSE / openSUSE Security Updates · Sep 27, 2026
- SUSE-SU-2026:23866-1 Security update for libsoup SUSE / openSUSE Security Updates · Sep 27, 2026
- openSUSE-SU-2026:21901-1 Security update for libsoup SUSE / openSUSE Security Updates · Sep 25, 2026
- SUSE-SU-2026:23848-1 Security update for libsoup SUSE / openSUSE Security Updates · Sep 23, 2026
- SUSE-SU-2026:4273-1 Security update for libsoup SUSE / openSUSE Security Updates · Sep 21, 2026
- SUSE-SU-2026:4274-1 Security update for libsoup SUSE / openSUSE Security Updates · Sep 21, 2026
- openSUSE-SU-2026:11823-1 libsoup-3_0-0-3.6.6-9.1 on GA media SUSE / openSUSE Security Updates · Sep 20, 2026