# CVE-2026-102559: Libsoup: libsoup: heap buffer overflow during websocket client-frame masking

CVE-2026-102559 is fixed in 20 products on 1 platform, first by RHSA-2026:93583, released September 3, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-102559
- Priority: High
- CVSS: 8.6 (Important)
- EPSS: 0.0063
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 3, 2026
- Weakness: Out-of-bounds Read
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-102559

## Description

A flaw was found in libsoup. When constructing a masked WebSocket client frame for a very large outgoing payload, size values passed to GByteArray allocation APIs could be truncated while the masking routine still used the full length, causing a heap buffer overflow.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | gir1.2-soup-2.4 Ubuntu 18.04.6 LTS (bionic) | 2.62.1-1ubuntu0.4+esm10 | [gir1.2-soup-2.4 2.62.1-1ubuntu0.4+esm10](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-gir1.2-soup-2.4-2.62.1-1ubuntu0.4-esm10.md) | Sep 30, 2026 |
| Linux | gir1.2-soup-2.4 Ubuntu 20.04 LTS (focal) | 2.70.0-1ubuntu0.5+esm5 | [gir1.2-soup-2.4 2.70.0-1ubuntu0.5+esm5](https://patchblox.com/security/data/fix/linux/ubuntu-focal-gir1.2-soup-2.4-2.70.0-1ubuntu0.5-esm5.md) | Sep 30, 2026 |
| Linux | gir1.2-soup-2.4 Ubuntu 22.04.1 LTS (jammy) | 2.74.2-3ubuntu0.10 | [gir1.2-soup-2.4 2.74.2-3ubuntu0.10](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-gir1.2-soup-2.4-2.74.2-3ubuntu0.10.md) | Sep 30, 2026 |
| Linux | gir1.2-soup-2.4 Ubuntu 24.04.5 LTS (noble) | 2.74.3-6ubuntu1.10 | [gir1.2-soup-2.4 2.74.3-6ubuntu1.10](https://patchblox.com/security/data/fix/linux/ubuntu-noble-gir1.2-soup-2.4-2.74.3-6ubuntu1.10.md) | Sep 30, 2026 |
| Linux | gir1.2-soup-2.4 Ubuntu 26.04.1 LTS (resolute) | 2.74.3-10.1ubuntu5+esm4 | [gir1.2-soup-2.4 2.74.3-10.1ubuntu5+esm4](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-gir1.2-soup-2.4-2.74.3-10.1ubuntu5-esm4.md) | Sep 30, 2026 |
| Linux | gir1.2-soup-3.0 Ubuntu 22.04.1 LTS (jammy) | 3.0.7-0ubuntu1+esm10 | [gir1.2-soup-3.0 3.0.7-0ubuntu1+esm10](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-gir1.2-soup-3.0-3.0.7-0ubuntu1-esm10.md) | Sep 30, 2026 |
| Linux | gir1.2-soup-3.0 Ubuntu 24.04.5 LTS (noble) | 3.4.4-5ubuntu0.10 | [gir1.2-soup-3.0 3.4.4-5ubuntu0.10](https://patchblox.com/security/data/fix/linux/ubuntu-noble-gir1.2-soup-3.0-3.4.4-5ubuntu0.10.md) | Sep 30, 2026 |
| Linux | gir1.2-soup-3.0 Ubuntu 26.04.1 LTS (resolute) | 3.6.6-1ubuntu0.2 | [gir1.2-soup-3.0 3.6.6-1ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-gir1.2-soup-3.0-3.6.6-1ubuntu0.2.md) | Sep 30, 2026 |
| Linux | libsoup RHEL 8 | 0:2.62.3-19.el8_10 | [RHSA-2026:84586](https://patchblox.com/security/data/fix/linux/rhsa-2026-84586.md) | Oct 19, 2026 |
| Linux | libsoup RHEL 9 | 0:2.72.0-16.el9_8.8 | [RHSA-2026:83384](https://patchblox.com/security/data/fix/linux/rhsa-2026-83384.md) | Oct 16, 2026 |
| Linux | libsoup almalinux 8 | 2.62.3-19.el8_10 | [ALSA-2026:84586](https://patchblox.com/security/data/fix/linux/alsa-2026-84586.md) | Nov 7, 2026 |
| Linux | libsoup almalinux 9 | 2.72.0-16.el9_8.8 | [ALSA-2026:83384](https://patchblox.com/security/data/fix/linux/alsa-2026-83384.md) | Nov 7, 2026 |
| Linux | libsoup amzn 2023 | 2.72.0-6.amzn2023.0.16 | [ALAS2023-2026-3212](https://patchblox.com/security/data/fix/linux/alas2023-2026-3212.md) | Nov 7, 2026 |
| Linux | libsoup ol 8 | 0:2.62.3-19.el8_10 | [ELSA-2026-84586](https://patchblox.com/security/data/fix/linux/elsa-2026-84586.md) | Nov 7, 2026 |
| Linux | libsoup ol 9 | 0:2.72.0-16.el9_8.8 | [ELSA-2026-83384](https://patchblox.com/security/data/fix/linux/elsa-2026-83384.md) | Nov 7, 2026 |
| Linux | libsoup opensuse-leap 16.0 | 3.6.6-160000.5.1 | [OPENSUSE-SU-2026:22181-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22181-1.md) | Nov 7, 2026 |
| Linux | libsoup rocky 8 | 0:2.62.3-19.el8_10 | [RLSA-2026:84586](https://patchblox.com/security/data/fix/linux/rlsa-2026-84586.md) | Nov 7, 2026 |
| Linux | libsoup rocky 9 | 0:2.72.0-16.el9_8.8 | [RLSA-2026:83384](https://patchblox.com/security/data/fix/linux/rlsa-2026-83384.md) | Nov 7, 2026 |
| Linux | libsoup sles 15.6 | 3.4.4-150600.3.59.1 | [SUSE-SU-2026:4631-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4631-1.md) | Nov 7, 2026 |
| Linux | libsoup sles 15.7 | 3.4.4-150600.3.59.1 | [SUSE-SU-2026:4631-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4631-1.md) | Nov 7, 2026 |
| Linux | libsoup sles 16.0 | 3.6.6-160000.5.1 | [SUSE-SU-2026:24470-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24470-1.md) | Nov 7, 2026 |
| Linux | libsoup-2.4-1 Ubuntu 24.04.5 LTS (noble) | 2.74.3-6ubuntu1.10 | [libsoup-2.4-1 2.74.3-6ubuntu1.10](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libsoup-2.4-1-2.74.3-6ubuntu1.10.md) | Sep 30, 2026 |
| Linux | libsoup-2.4-1 Ubuntu 26.04.1 LTS (resolute) | 2.74.3-10.1ubuntu5+esm4 | [libsoup-2.4-1 2.74.3-10.1ubuntu5+esm4](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libsoup-2.4-1-2.74.3-10.1ubuntu5-esm4.md) | Sep 30, 2026 |
| Linux | libsoup-3.0-0 Ubuntu 22.04.1 LTS (jammy) | 3.0.7-0ubuntu1+esm10 | [libsoup-3.0-0 3.0.7-0ubuntu1+esm10](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libsoup-3.0-0-3.0.7-0ubuntu1-esm10.md) | Sep 30, 2026 |
| Linux | libsoup-3.0-0 Ubuntu 24.04.5 LTS (noble) | 3.4.4-5ubuntu0.10 | [libsoup-3.0-0 3.4.4-5ubuntu0.10](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libsoup-3.0-0-3.4.4-5ubuntu0.10.md) | Sep 30, 2026 |
| Linux | libsoup-3.0-0 Ubuntu 26.04.1 LTS (resolute) | 3.6.6-1ubuntu0.2 | [libsoup-3.0-0 3.6.6-1ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libsoup-3.0-0-3.6.6-1ubuntu0.2.md) | Sep 30, 2026 |
| Linux | libsoup-3.0-common Ubuntu 22.04.1 LTS (jammy) | 3.0.7-0ubuntu1+esm10 | [libsoup-3.0-common 3.0.7-0ubuntu1+esm10](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libsoup-3.0-common-3.0.7-0ubuntu1-esm10.md) | Sep 30, 2026 |
| Linux | libsoup-3.0-common Ubuntu 24.04.5 LTS (noble) | 3.4.4-5ubuntu0.10 | [libsoup-3.0-common 3.4.4-5ubuntu0.10](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libsoup-3.0-common-3.4.4-5ubuntu0.10.md) | Sep 30, 2026 |
| Linux | libsoup-3.0-common Ubuntu 26.04.1 LTS (resolute) | 3.6.6-1ubuntu0.2 | [libsoup-3.0-common 3.6.6-1ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libsoup-3.0-common-3.6.6-1ubuntu0.2.md) | Sep 30, 2026 |
| Linux | libsoup-3.0-tests Ubuntu 22.04.1 LTS (jammy) | 3.0.7-0ubuntu1+esm10 | [libsoup-3.0-tests 3.0.7-0ubuntu1+esm10](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libsoup-3.0-tests-3.0.7-0ubuntu1-esm10.md) | Sep 30, 2026 |
| Linux | libsoup-3.0-tests Ubuntu 24.04.5 LTS (noble) | 3.4.4-5ubuntu0.10 | [libsoup-3.0-tests 3.4.4-5ubuntu0.10](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libsoup-3.0-tests-3.4.4-5ubuntu0.10.md) | Sep 30, 2026 |
| Linux | libsoup-3.0-tests Ubuntu 26.04.1 LTS (resolute) | 3.6.6-1ubuntu0.2 | [libsoup-3.0-tests 3.6.6-1ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libsoup-3.0-tests-3.6.6-1ubuntu0.2.md) | Sep 30, 2026 |
| Linux | libsoup-debuginfo amzn 2023 | 2.72.0-6.amzn2023.0.16 | [ALAS2023-2026-3212](https://patchblox.com/security/data/fix/linux/alas2023-2026-3212.md) | Nov 7, 2026 |
| Linux | libsoup-debugsource amzn 2023 | 2.72.0-6.amzn2023.0.16 | [ALAS2023-2026-3212](https://patchblox.com/security/data/fix/linux/alas2023-2026-3212.md) | Nov 7, 2026 |
| Linux | libsoup-devel RHEL 8 | 0:2.62.3-19.el8_10 | [RHSA-2026:84586](https://patchblox.com/security/data/fix/linux/rhsa-2026-84586.md) | Oct 19, 2026 |
| Linux | libsoup-devel RHEL 9 | 0:2.72.0-16.el9_8.8 | [RHSA-2026:83384](https://patchblox.com/security/data/fix/linux/rhsa-2026-83384.md) | Oct 16, 2026 |
| Linux | libsoup-devel almalinux 8 | 2.62.3-19.el8_10 | [ALSA-2026:84586](https://patchblox.com/security/data/fix/linux/alsa-2026-84586.md) | Nov 7, 2026 |
| Linux | libsoup-devel almalinux 9 | 2.72.0-16.el9_8.8 | [ALSA-2026:83384](https://patchblox.com/security/data/fix/linux/alsa-2026-83384.md) | Nov 7, 2026 |
| Linux | libsoup-devel amzn 2023 | 2.72.0-6.amzn2023.0.16 | [ALAS2023-2026-3212](https://patchblox.com/security/data/fix/linux/alas2023-2026-3212.md) | Nov 7, 2026 |
| Linux | libsoup-devel ol 8 | 0:2.62.3-19.el8_10 | [ELSA-2026-84586](https://patchblox.com/security/data/fix/linux/elsa-2026-84586.md) | Nov 7, 2026 |
| Linux | libsoup-devel ol 9 | 0:2.72.0-16.el9_8.8 | [ELSA-2026-83384](https://patchblox.com/security/data/fix/linux/elsa-2026-83384.md) | Nov 7, 2026 |
| Linux | libsoup-doc amzn 2023 | 2.72.0-6.amzn2023.0.16 | [ALAS2023-2026-3212](https://patchblox.com/security/data/fix/linux/alas2023-2026-3212.md) | Nov 7, 2026 |
| Linux | libsoup-gnome-2.4-1 Ubuntu 24.04.5 LTS (noble) | 2.74.3-6ubuntu1.10 | [libsoup-gnome-2.4-1 2.74.3-6ubuntu1.10](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libsoup-gnome-2.4-1-2.74.3-6ubuntu1.10.md) | Sep 30, 2026 |
| Linux | libsoup-gnome-2.4-1 Ubuntu 26.04.1 LTS (resolute) | 2.74.3-10.1ubuntu5+esm4 | [libsoup-gnome-2.4-1 2.74.3-10.1ubuntu5+esm4](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libsoup-gnome-2.4-1-2.74.3-10.1ubuntu5-esm4.md) | Sep 30, 2026 |
| Linux | libsoup-gnome2.4-1 Ubuntu 18.04.6 LTS (bionic) | 2.62.1-1ubuntu0.4+esm10 | [libsoup-gnome2.4-1 2.62.1-1ubuntu0.4+esm10](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libsoup-gnome2.4-1-2.62.1-1ubuntu0.4-esm10.md) | Sep 30, 2026 |
| Linux | libsoup-gnome2.4-1 Ubuntu 20.04 LTS (focal) | 2.70.0-1ubuntu0.5+esm5 | [libsoup-gnome2.4-1 2.70.0-1ubuntu0.5+esm5](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libsoup-gnome2.4-1-2.70.0-1ubuntu0.5-esm5.md) | Sep 30, 2026 |
| Linux | libsoup-gnome2.4-1 Ubuntu 22.04.1 LTS (jammy) | 2.74.2-3ubuntu0.10 | [libsoup-gnome2.4-1 2.74.2-3ubuntu0.10](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libsoup-gnome2.4-1-2.74.2-3ubuntu0.10.md) | Sep 30, 2026 |
| Linux | libsoup2 sles 15.6 | 2.74.3-150600.4.42.1 | [SUSE-SU-2026:4703-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4703-1.md) | Nov 7, 2026 |
| Linux | libsoup2 sles 15.7 | 2.74.3-150600.4.42.1 | [SUSE-SU-2026:4703-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4703-1.md) | Nov 7, 2026 |
| Linux | libsoup2.4-1 Ubuntu 18.04.6 LTS (bionic) | 2.62.1-1ubuntu0.4+esm10 | [libsoup2.4-1 2.62.1-1ubuntu0.4+esm10](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libsoup2.4-1-2.62.1-1ubuntu0.4-esm10.md) | Sep 30, 2026 |
| Linux | libsoup2.4-1 Ubuntu 20.04 LTS (focal) | 2.70.0-1ubuntu0.5+esm5 | [libsoup2.4-1 2.70.0-1ubuntu0.5+esm5](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libsoup2.4-1-2.70.0-1ubuntu0.5-esm5.md) | Sep 30, 2026 |
| Linux | libsoup2.4-1 Ubuntu 22.04.1 LTS (jammy) | 2.74.2-3ubuntu0.10 | [libsoup2.4-1 2.74.2-3ubuntu0.10](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libsoup2.4-1-2.74.2-3ubuntu0.10.md) | Sep 30, 2026 |
| Linux | libsoup2.4-common Ubuntu 22.04.1 LTS (jammy) | 2.74.2-3ubuntu0.10 | [libsoup2.4-common 2.74.2-3ubuntu0.10](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libsoup2.4-common-2.74.2-3ubuntu0.10.md) | Sep 30, 2026 |
| Linux | libsoup2.4-common Ubuntu 24.04.5 LTS (noble) | 2.74.3-6ubuntu1.10 | [libsoup2.4-common 2.74.3-6ubuntu1.10](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libsoup2.4-common-2.74.3-6ubuntu1.10.md) | Sep 30, 2026 |
| Linux | libsoup2.4-common Ubuntu 26.04.1 LTS (resolute) | 2.74.3-10.1ubuntu5+esm4 | [libsoup2.4-common 2.74.3-10.1ubuntu5+esm4](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libsoup2.4-common-2.74.3-10.1ubuntu5-esm4.md) | Sep 30, 2026 |
| Linux | libsoup2.4-tests Ubuntu 20.04 LTS (focal) | 2.70.0-1ubuntu0.5+esm5 | [libsoup2.4-tests 2.70.0-1ubuntu0.5+esm5](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libsoup2.4-tests-2.70.0-1ubuntu0.5-esm5.md) | Sep 30, 2026 |
| Linux | libsoup2.4-tests Ubuntu 22.04.1 LTS (jammy) | 2.74.2-3ubuntu0.10 | [libsoup2.4-tests 2.74.2-3ubuntu0.10](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libsoup2.4-tests-2.74.2-3ubuntu0.10.md) | Sep 30, 2026 |
| Linux | libsoup2.4-tests Ubuntu 24.04.5 LTS (noble) | 2.74.3-6ubuntu1.10 | [libsoup2.4-tests 2.74.3-6ubuntu1.10](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libsoup2.4-tests-2.74.3-6ubuntu1.10.md) | Sep 30, 2026 |
| Linux | libsoup2.4-tests Ubuntu 26.04.1 LTS (resolute) | 2.74.3-10.1ubuntu5+esm4 | [libsoup2.4-tests 2.74.3-10.1ubuntu5+esm4](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libsoup2.4-tests-2.74.3-10.1ubuntu5-esm4.md) | Sep 30, 2026 |
| Linux | libsoup3 RHEL 10 | 3.6.5-3.el10_0.19 | [RHSA-2026:93583](https://patchblox.com/security/data/fix/linux/rhsa-2026-93583.md) | Sep 3, 2026 |
| Linux | libsoup3 almalinux 10 | 3.6.5-3.el10_2.20 | [ALSA-2026:83618](https://patchblox.com/security/data/fix/linux/alsa-2026-83618.md) | Nov 7, 2026 |
| Linux | libsoup3 ol 10 | 0:3.6.5-3.el10_2.20 | [ELSA-2026-83618](https://patchblox.com/security/data/fix/linux/elsa-2026-83618.md) | Nov 7, 2026 |
| Linux | libsoup3-devel almalinux 10 | 3.6.5-3.el10_2.20 | [ALSA-2026:83618](https://patchblox.com/security/data/fix/linux/alsa-2026-83618.md) | Nov 7, 2026 |
| Linux | libsoup3-devel ol 10 | 0:3.6.5-3.el10_2.20 | [ELSA-2026-83618](https://patchblox.com/security/data/fix/linux/elsa-2026-83618.md) | Nov 7, 2026 |
| Linux | libsoup3-doc almalinux 10 | 3.6.5-3.el10_2.20 | [ALSA-2026:83618](https://patchblox.com/security/data/fix/linux/alsa-2026-83618.md) | Nov 7, 2026 |
| Linux | libsoup3-doc ol 10 | 0:3.6.5-3.el10_2.20 | [ELSA-2026-83618](https://patchblox.com/security/data/fix/linux/elsa-2026-83618.md) | Nov 7, 2026 |

---

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