CVE-2026-114213 json
WebSocket 1-byte continuation frames bypass `max_fragmented_message_size` in Bandit
published 2026-10-26 13 d ago modified 2026-10-26 13 d ago also EEF-CVE-2026-114213 , GHSA-cpx7-qf6w-jc63 , EUVD-2026-109821
- cvss
- 8.7
- version 4.0, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.6%
- EPSS 0.6% chance of exploitation in 30 days, percentile 49%
- public exploits
- 0
- none known
Summary
Allocation of Resources Without Limits or Throttling vulnerability in the WebSocket fragment reassembly of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory via a fragmented message made of many 1-byte continuation frames.
Bandit.WebSocket.Connection checks max_fragmented_message_size against the payload bytes received, but keeps every non-final continuation frame as a new list cell around its own binary, and nothing limits the number of fragments. A 1-byte fragment costs 7 bytes on the wire but about 150 to 170 bytes of server memory, so one connection can hold about 150 times the configured limit, roughly 1.2 to 1.4 GB at the default 8 MB. Ping frames between fragments keep the connection alive past the idle timeout.
This issue affects bandit: from 1.11.0 before 1.14.0.
Patch / fix
- hex bandit 1.14.0
- mtrudel bandit 1.14.0
CISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 13 d ago
Exploit prediction
0.60% chance of exploitation in the next 30 days, higher than 49% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 8.7 | 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 |
| CNA | 4.0 | 8.7 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| hex | bandit | >=1.11.0, <1.14.0 |
1.14.0 |
Affected products
- mtrudel bandit
Classification
- Weakness
-
- CWE-770 Allocation of Resources Without Limits or Throttling
References
-
github.com
/mtrudel/bandit/commit/21612c7c7b1ce43eccd36d3af3a2299d23513667
related, web
-
github.com
/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a
patch
-
github.com
/mtrudel/bandit/security/advisories/GHSA-cpx7-qf6w-jc63
vendor-advisory, related, advisory
-
cna.erlef.org
/cves/CVE-2026-114213.html
related, web
-
osv.dev
/vulnerability/EEF-CVE-2026-114213
related
-
hex.pm
/packages/bandit
package
Sources
- CVE List CVE-2026-114213
- NVD CVE-2026-114213
- OSV EEF-CVE-2026-114213
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