---
title: "CVE-2026-102557: libsoup - Out of Bounds Read/Write"
description: "libsoup contains a heap corruption caused by improper size capping when reassembling fragmented WebSocket messages into a GByteArray, letting remote attackers cause crashes or memory corruption, exploit requires sending crafted WebSocket fragments."
url: https://panop.io/threat-heartbeat/CVE-2026-102557/
---

# CVE-2026-102557 libsoup - Out of Bounds Read/Write

libsoup contains a heap corruption caused by improper size capping when reassembling fragmented WebSocket messages into a GByteArray, letting remote attackers cause crashes or memory corruption, exploit requires sending crafted WebSocket fragments.

CVSS base score 8.6 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.22% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-102557)

## Details

Type

Out of Bounds Read/Write

Impact

Denial Of Service

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

Published

29 September 2026

Updated

15 October 2026

Weakness

[CWE-125](https://cwe.mitre.org/data/definitions/125.html)

## Vendor fix

Update to the latest version of libsoup.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-102557](https://nvd.nist.gov/vuln/detail/CVE-2026-102557)
- [https://access.redhat.com/security/cve/CVE-2026-102557](https://access.redhat.com/security/cve/CVE-2026-102557)
- [https://bugzilla.redhat.com/show\_bug.cgi?id=2543231](https://bugzilla.redhat.com/show_bug.cgi?id=2543231)
- [https://access.redhat.com/errata/RHSA-2026:83384](https://access.redhat.com/errata/RHSA-2026:83384)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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