High [CVE-2026-102559] Libsoup: libsoup: heap buffer overflow during websocket client-frame masking
This high-severity Red Hat Linux advisory covers CVE-2026-102559 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
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Summary
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.
This issue is rated Important. Triggering requires causing a libsoup WebSocket client (or client-role connection) to send an extremely large message.
That may be reachable when application-level message size is attacker-influenced. Impact is heap corruption or denial of service in the sending process.
Red Hat severity: Important — CVSS 8.6 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H). Weakness: CWE-125.
Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9. Will not fix / out of support: Red Hat Enterprise Linux 6.
Red Hat does not currently list a fixing RHSA for this CVE.
Affected products named by the advisory: Red Hat package: libsoup3.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 1 day ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 1 day ago·verify at source
Mitigation checklist
- To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.
Official advisory · high-confidence parse· fetched 1 day ago·verify at source
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