CVE-2026-102559
Received Received - Intake

Heap Buffer Overflow in libsoup WebSocket Client

Publication date: 2026-09-29

Last updated on: 2026-09-29

Assigner: redhat-SADP

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.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-09-29
Last Modified
2026-09-29
Generated
2026-09-29
AI Q&A
2026-09-29
EPSS Evaluated
N/A
NVD
CVE-2026-102559
EUVD
EUVD-2026-89104

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
gnome libsoup 3.7.3
libsoup libsoup *

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-125 The product reads data past the end, or before the beginning, of the intended buffer.

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

This vulnerability is a heap buffer overflow in libsoup. It occurs when creating a masked WebSocket client frame for a very large payload. The issue arises because size values used in GByteArray allocation APIs can be truncated, but the masking routine still uses the full length, leading to memory corruption.

Impact Analysis

An attacker could exploit this flaw to execute arbitrary code, crash the application, or cause other unintended behavior by sending a specially crafted WebSocket frame. This may lead to data loss, service disruption, or unauthorized access depending on the application's context.

Mitigation Strategies

Update libsoup to the latest patched version immediately to address the heap buffer overflow in WebSocket frame handling. Monitor network traffic for unusual payload sizes or anomalies in WebSocket communications.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-102559. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart