CVE-2026-39804Public exploitNetwork attack vector

Unauthenticated node crash via unbounded WebSocket inflate

Published May 1, 2026 · Updated May 1, 2026

Allocation exhaustion in Mat Trudel Bandit 0.5.9 through 1.10.4 allows remote attackers to crash the BEAM node via a compressed WebSocket frame. Bandit.WebSocket.PerMessageDeflate.inflate/2 passes attacker-controlled data to zlib.inflate/2 without an output cap, then materializes the full result as one binary. Reachability requires server-level compression and compress: true on the WebSocket upgrade; one high-ratio frame can exhaust node memory before application code runs.

CVSS severity8.2
High
EPSS probability0.63%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Allocation exhaustion in Mat Trudel Bandit 0.5.9 through 1.10.4 allows remote attackers to crash the BEAM node via a compressed WebSocket frame. Bandit.WebSocket.PerMessageDeflate.inflate/2 passes attacker-controlled data to zlib.inflate/2 without an output cap, then materializes the full result as one binary. Reachability requires server-level compression and compress: true on the WebSocket upgrade; one high-ratio frame can exhaust node memory before application code runs.

The record

CVE
CVE-2026-39804
Published
May 1, 2026
Updated
May 1, 2026
Vendor
Mat Trudel
Product
Bandit
Classifications
CWE-770, CAPEC-130, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 1, 2026CVE publishedPublication date reported by the CVE source.
  2. May 1, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0.5.9 <1.11.0
  2. Affected versionversion=da4027cff7d2b80319e76fe7a32f84beceec490a <1.11.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mat Trudel · Banditversion=0.5.9 <1.11.0; version=da4027cff7d2b80319e76fe7a32f84beceec490a <1.11.0

Published CVSS scores

8.2Erlang Ecosystem FoundationCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
CAPEC-130Excessive Allocation
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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