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VulnerabilityPublished Updated

CVE-2026-42786: mtrudel bandit · Unthrottled Resource Allocation

Affects mtrudel banditSource CVE Database V5

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Not known to be exploited · CVSS 8.7 High : upgrade to 1.11.0 soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score
8.7High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.6% chance of exploitation in 30 days – higher than 50% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.11.0, 21612c7c7b1ce43eccd36d3af3a2299d23513667
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 1 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade bandit to 1.11.0; bandit to 21612c7c7b1ce43eccd36d3af3a2299d23513667.

Affected software

ProductAffectedFixed in
mtrudelbanditAffected
  • >=0.5.0 <1.11.0
Fixed in
  • 1.11.0
mtrudelbanditAffected
  • ≥ 8909391f486d42138c5308410bc5ea49a65f4d46, < 21612c7c7b1ce43eccd36d3af3a2299d23513667
Fixed in
  • 21612c7c7b1ce43eccd36d3af3a2299d23513667
Hexbanditpkg:hex/banditOther threatsAffected
  • =0.5.0
Fixed in–
Hexbanditpkg:hex/banditOther threatsAffected
  • >=0.5.0 <1.11.0
Fixed in
  • 1.11.0

CPE configurations (1)

  • cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, consider implementing external protections such as limiting WebSocket connection rates or employing upstream WebSocket proxies that enforce frame size and connection duration limits.

Description

Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion. The fragment reassembly path in 'Elixir.Bandit.WebSocket.Connection':handle_frame/3 in lib/bandit/websocket/connection.ex appends every incoming Continuation{fin: false} frame's payload to a per-connection iolist with no cumulative size cap. The existing max_frame_size option only bounds individual frames; a peer that streams an unbounded number of continuation frames without ever setting fin=1 grows BEAM heap linearly until the OS or a supervisor kills the process. Because the accumulation happens before WebSock.handle_in/2 is called, the application has no opportunity to interpose a size check. Phoenix Channels and LiveView both run over WebSock on Bandit, so a stock Phoenix application exposes this surface as soon as it accepts socket connections. This issue affects bandit: from 0.5.0 before 1.11.0.

References

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