CVE-2026-15709

7.5 HIGH 0.9% exploit odds No fix listed Denial of service

What it is

A flaw was found in libsoup's WebSocket implementation when using the permessage-deflate extension. The extension's decompression loop (inflate()) processes data in chunks without enforcing an upper boundary limit on the output buffer size. While libsoup limits the incoming compressed frame size via max_incoming_payload_size, it fails to track or limit memory allocation during decompression. A separate check for decompressed size (max_total_message_size) exists but executes only after inflation is complete, and it is entirely disabled by default for client connections. A remote, unauthenticated attacker can exploit this by sending a small, highly compressed payload (a decompression bomb), causing unbounded memory allocation that triggers an Out-of-Memory (OOM) crash and a Denial of Service (DoS).

At a glance

Exploitability: Can be exploited over the network without logging in. High risk of service disruption.
Exploit odds: 0.9% chance of exploitation in the next 30 days (EPSS).
Fix: No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

2026-07-14 20:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-11-05 17:18 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.9% in the next 30 days (EPSS).
Severity: 7.5 HIGH (CVSS).
Fix: none linked yet, which raises it.

Details

Published: 2026-07-14 20:16 UTC
Last modified: 2026-11-05 17:18 UTC
Exploit probability: 0.9% · EPSS, next 30 days
Weakness: CWE-409
Record status: Deferred

Attack profile CVSS 3.1 · 7.5

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Raw vector

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

Is it in your code?

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Read https://cve-list.com/agent/cve/CVE-2026-15709.md and follow it. Check whether this project is affected by CVE-2026-15709. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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References

NVD record · CVE.org record