CVE-2026-53524

MEDIUM

6.5

CVSS v3

Description

WeeChat (Wee Enhanced Environment for Chat) is a free chat client. In versions 4.3.0 through 4.9.0, the WeeChat relay module's WebSocket permessage-deflate decompression function relay_websocket_inflate() has no upper bound on output size. An authenticated relay user can send a small compressed WebSocket frame (~100 bytes) that decompresses to gigabytes, exhausting all server memory and crashing the entire WeeChat process. The api protocol enables permessage-deflate and requires authentication before WebSocket upgrade. Version 4.9.1 patches the issue.

CWE-409

How to fix

Remediation Available

weechatDebian

Fixed in:4.9.3-1CVE-2026-53524

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Exploit Intelligence

0.27%probability of exploitation in 30 days

19thpercentile

Low risk: more likely to be exploited than 19% of all known CVEs.

References

Other references1

github.com

Related Vulnerabilities

Other CWE-409 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2026-49975	High	7.5	31%	-	Fix
CVE-2026-21441	High	7.5	2.8%	-	Fix
CVE-2024-43499	High	7.5	2.6%	-	Fix
CVE-2024-28180	Medium	4.3	2.0%	-	Fix
CVE-2017-16129	Medium	5.9	1.8%	-	Fix
CVE-2022-29225	High	7.5	1.6%	-	Fix

Common questions

How do I fix CVE-2026-53524?

Upgrade weechat on debian unstable to 4.9.3-1 or later.

Is CVE-2026-53524 being actively exploited?

Not that we know of. CVE-2026-53524 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.27% is the estimated probability that it will be exploited in the next 30 days. That is higher than 19% of all scored CVEs.

How severe is CVE-2026-53524?

CVE-2026-53524 has a CVSS v3 base score of 6.5, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-53524 affect?

Published advisories record a fix for weechat (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-24.