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Medium 6.5Published Aug 21, 2026

CVE-2026-53524WeeChat has a Decompression Bomb in Relay WebSocket (DoS)

Updated under an hour ago ()

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It affects weechat. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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.

CVSS
6.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE)
CWE-409
Known exploited
Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days)
Not loaded for this CVE
Assigned by
GitHub_M
NVD analysis
Deferred
Record last updated
Aug 24, 2026
First seen by InfoSec Signals
Oct 9, 2026

Affected products

Affected products
weechat weechat
weechat:weechat (from the name)
from 4.3.0, < 4.9.1
CNA record

References

  • x-refsource-confirm

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.

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