# CVE-2026-85534: Libsoup: libsoup: http/2 client crash in on_data_source_read_callback when settings initial_window_size shrinks during deferred body read CVE-2026-85534 is fixed in 10 products on 1 platform, first by gir1.2-soup-3.0 3.0.7-0ubuntu1+esm9, released September 4, 2026. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2026-85534 - Priority: Routine - CVSS: 5.9 (Moderate) - EPSS: 0.0032 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Sep 4, 2026 - Weakness: Reachable Assertion - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85534 ## 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. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | gir1.2-soup-3.0 Ubuntu 22.04.1 LTS (jammy) | 3.0.7-0ubuntu1+esm9 | [gir1.2-soup-3.0 3.0.7-0ubuntu1+esm9](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-gir1.2-soup-3.0-3.0.7-0ubuntu1-esm9.md) | Sep 4, 2026 | | Linux | gir1.2-soup-3.0 Ubuntu 24.04.5 LTS (noble) | 3.4.4-5ubuntu0.9 | [gir1.2-soup-3.0 3.4.4-5ubuntu0.9](https://patchblox.com/security/data/fix/linux/ubuntu-noble-gir1.2-soup-3.0-3.4.4-5ubuntu0.9.md) | Sep 4, 2026 | | Linux | gir1.2-soup-3.0 Ubuntu 26.04.1 LTS (resolute) | 3.6.6-1ubuntu0.1 | [gir1.2-soup-3.0 3.6.6-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-gir1.2-soup-3.0-3.6.6-1ubuntu0.1.md) | Sep 4, 2026 | | Linux | libsoup opensuse-leap 16.0 | 3.6.6-160000.4.1 | [OPENSUSE-SU-2026:21901-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21901-1.md) | Sep 21, 2026 | | Linux | libsoup sles 15.6 | 3.4.4-150600.3.53.1 | [SUSE-SU-2026:4273-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4273-1.md) | Sep 21, 2026 | | Linux | libsoup sles 15.7 | 3.4.4-150600.3.53.1 | [SUSE-SU-2026:4273-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4273-1.md) | Sep 21, 2026 | | Linux | libsoup sles 16.0 | 3.6.6-160000.4.1 | [SUSE-SU-2026:23866-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-23866-1.md) | Sep 21, 2026 | | Linux | libsoup-3.0-0 Ubuntu 22.04.1 LTS (jammy) | 3.0.7-0ubuntu1+esm9 | [libsoup-3.0-0 3.0.7-0ubuntu1+esm9](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libsoup-3.0-0-3.0.7-0ubuntu1-esm9.md) | Sep 4, 2026 | | Linux | libsoup-3.0-0 Ubuntu 24.04.5 LTS (noble) | 3.4.4-5ubuntu0.9 | [libsoup-3.0-0 3.4.4-5ubuntu0.9](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libsoup-3.0-0-3.4.4-5ubuntu0.9.md) | Sep 4, 2026 | | Linux | libsoup-3.0-0 Ubuntu 26.04.1 LTS (resolute) | 3.6.6-1ubuntu0.1 | [libsoup-3.0-0 3.6.6-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libsoup-3.0-0-3.6.6-1ubuntu0.1.md) | Sep 4, 2026 | | Linux | libsoup-3.0-common Ubuntu 22.04.1 LTS (jammy) | 3.0.7-0ubuntu1+esm9 | [libsoup-3.0-common 3.0.7-0ubuntu1+esm9](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libsoup-3.0-common-3.0.7-0ubuntu1-esm9.md) | Sep 4, 2026 | | Linux | libsoup-3.0-common Ubuntu 24.04.5 LTS (noble) | 3.4.4-5ubuntu0.9 | [libsoup-3.0-common 3.4.4-5ubuntu0.9](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libsoup-3.0-common-3.4.4-5ubuntu0.9.md) | Sep 4, 2026 | | Linux | libsoup-3.0-common Ubuntu 26.04.1 LTS (resolute) | 3.6.6-1ubuntu0.1 | [libsoup-3.0-common 3.6.6-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libsoup-3.0-common-3.6.6-1ubuntu0.1.md) | Sep 4, 2026 | | Linux | libsoup-3.0-tests Ubuntu 22.04.1 LTS (jammy) | 3.0.7-0ubuntu1+esm9 | [libsoup-3.0-tests 3.0.7-0ubuntu1+esm9](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libsoup-3.0-tests-3.0.7-0ubuntu1-esm9.md) | Sep 4, 2026 | | Linux | libsoup-3.0-tests Ubuntu 24.04.5 LTS (noble) | 3.4.4-5ubuntu0.9 | [libsoup-3.0-tests 3.4.4-5ubuntu0.9](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libsoup-3.0-tests-3.4.4-5ubuntu0.9.md) | Sep 4, 2026 | | Linux | libsoup-3.0-tests Ubuntu 26.04.1 LTS (resolute) | 3.6.6-1ubuntu0.1 | [libsoup-3.0-tests 3.6.6-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libsoup-3.0-tests-3.6.6-1ubuntu0.1.md) | Sep 4, 2026 | | Linux | libsoup3 amzn 2023 | 3.7.2-1.amzn2023 | [ALAS2023-2026-3144](https://patchblox.com/security/data/fix/linux/alas2023-2026-3144.md) | Sep 28, 2026 | | Linux | libsoup3-debuginfo amzn 2023 | 3.7.2-1.amzn2023 | [ALAS2023-2026-3144](https://patchblox.com/security/data/fix/linux/alas2023-2026-3144.md) | Sep 28, 2026 | | Linux | libsoup3-debugsource amzn 2023 | 3.7.2-1.amzn2023 | [ALAS2023-2026-3144](https://patchblox.com/security/data/fix/linux/alas2023-2026-3144.md) | Sep 28, 2026 | | Linux | libsoup3-devel amzn 2023 | 3.7.2-1.amzn2023 | [ALAS2023-2026-3144](https://patchblox.com/security/data/fix/linux/alas2023-2026-3144.md) | Sep 28, 2026 | | Linux | libsoup3-doc amzn 2023 | 3.7.2-1.amzn2023 | [ALAS2023-2026-3144](https://patchblox.com/security/data/fix/linux/alas2023-2026-3144.md) | Sep 28, 2026 | --- Data as of 2026-11-08T00:53:09Z UTC. 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