CVE-2026-102559
High
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.
SeverityHigh
CVSS8.6
Exploit probability—
Product
Gnome Libsoup
PublishedSep 29, 2026
First seenSep 29, 2026
Weakness typeCWE-125Out-of-bounds read
How to fix
Update
- gnome libsoup3.7.3 or later
Vendor advisories
- access.redhat.com/security/cve/CVE-2026-102559
- access.redhat.com/errata/RHSA-2026:83384
- access.redhat.com/errata/RHSA-2026:83618
- access.redhat.com/errata/RHSA-2026:84586
- access.redhat.com/errata/RHSA-2026:92347
- access.redhat.com/errata/RHSA-2026:93445
- access.redhat.com/errata/RHSA-2026:93446
- access.redhat.com/errata/RHSA-2026:93447
- access.redhat.com/errata/RHSA-2026:93465
- access.redhat.com/errata/RHSA-2026:93466
- access.redhat.com/errata/RHSA-2026:93583
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| gnome libsoup | v < 3.7.3 | 3.7.3 |
| redhat enterprise_linux | 7.0, 8.0, 9.0, 10.0 | — |
| microsoft azl3_libsoup_3.4.4-16 | No range specified | — |
| microsoft azl3_libsoup_3.4.4-18 | No range specified | — |
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