High severity · published Oct 26, 2026
CVE-2026-114213
WebSocket 1-byte continuation frames bypass `max_fragmented_message_size` in Bandit
New
8.7
CVSS
0.6%
EPSS
No
On KEV
Description
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.
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 49% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
BA
bandit · mtrudel
1.11.0 before 1.14.0; 21612c7c7b1ce43eccd36d3af3a2299d23513667 before 220b9dfd27f9a21305be2afc75cbe585ddc24e7a · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-114213
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-114213
cna.erlef.org
https://cna.erlef.org/cves/CVE-2026-114213.html
github.com
https://github.com/mtrudel/bandit/commit/21612c7c7b1ce43eccd36d3af3a2299d23513667
github.com
https://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a
github.com
https://github.com/mtrudel/bandit/security/advisories/GHSA-cpx7-qf6w-jc63
osv.dev
https://osv.dev/vulnerability/EEF-CVE-2026-114213
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