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TI-2026-38598 Aliases CVE-2026-53524

WeeChat has a Decompression Bomb in Relay WebSocket (DoS)

Priority MEDIUM 62CWE-409Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00484 41st percentileScored 2026-11-07
Fix Fixed weechat (weechat): 4.9.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
weechatweechat4.3.0 to before 4.9.14.9.1Patch availableCNA
  • weechat Vendorweechat Affected 4.3.0 to before 4.9.1 Fixed in 4.9.1 Patch available CNA

Remediation

  • Fix · CNA weechat (weechat) Fixed in 4.9.1

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-53524

References

Other 1

  • TI-2026-38599 WeeChat has Non-Constant-Time Password Hash Comparison in Relay Authentication CVSS 3.1HIGH 7.4
  • TI-2020-07189 irc_mode_channel_update in plugins/irc/irc-mode.c in WeeChat through 2.7 allows remote… CVSS 3.1CRITICAL 9.8
  • TI-2020-07845 An issue was discovered in WeeChat before 2.7.1 (0.3.4 to 2.7 are affected). CVSS 3.1CRITICAL 9.8
  • TI-2024-31065 WeeChat before 4.4.2 has an integer overflow and resultant buffer overflow at… CVSS 3.1CRITICAL 9.8
  • TI-2017-10792 logger.c in the logger plugin in WeeChat before 1.9.1 allows a crash via strftime… CVSS 3.0HIGH 7.5
  • TI-2017-05663 WeeChat before 1.7.1 allows a remote crash by sending a filename via DCC to the IRC… CVSS 3.0HIGH 7.5
See all 8 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences