# CVE-2026-110314: WebSocket frames keep reaching the WebSock after a server-initiated close in Bandit

Status: published. Published: 2026-10-26. Updated: 2026-11-02.

Client-Side Enforcement of Server-Side Security vulnerability in the WebSocket connection handling of mtrudel bandit allows a remote client to keep running WebSock handler code after the server has stopped its connection, via data frames sent after ignoring the server's Close frame.

When a WebSock callback returns {:stop, ...}, Bandit.WebSocket.Connection calls terminate/2, sends Close and shuts down the write side, but keeps the connection process running in a :closing state. handle_frame/3 and handle_info/3 never check that state, so later frames still reach handle_in/2 and later messages reach handle_info/2, with the state from the stop tuple, until the client sends Close, TCP drops or the idle timeout fires. A client refused in init/1 after a failed token check could still run an admin-only action.

This issue affects bandit: from 0.5.1 before 1.14.0.

## Remediation

- workaround: Mark the WebSock state as stopped whenever a callback returns {:stop, ...}, and have handle_in/2 and handle_info/2 return {:ok, state} without acting while that mark is set. (source: CNA: EEF)
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: EEF) — https://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a

## Affected products and versions

- mtrudel / bandit (bandit): ≥ 0.5.1; < 1.14.0 (affected, semver). Source: CNA: EEF
- mtrudel / bandit (mtrudel/bandit): ≥ bb407f2277dcb65a58dd8cc07913a0b58a80e266; < 220b9dfd27f9a21305be2afc75cbe585ddc24e7a (affected, git). Source: CNA: EEF

## Severity and prioritization

- CVSS 4.0: 6.3 (medium); CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N; source: CNA: EEF

- CVSS 4.0: 6.3 (medium); CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/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; source: NVD: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

- CISA KEV: No listing in collected sources

- EPSS: 0.38% as of 2026-11-02; percentile 32.45%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-602

## Exploit evidence

- exploit: https://github.com/mtrudel/bandit/security/advisories/GHSA-2v5v-8f9v-xh85 (ADP: CISA-ADP)

## References

- https://github.com/mtrudel/bandit/security/advisories/GHSA-2v5v-8f9v-xh85 (CNA: EEF; vendor-advisory, related)

- https://cna.erlef.org/cves/CVE-2026-110314.html (CNA: EEF; related)

- https://osv.dev/vulnerability/EEF-CVE-2026-110314 (CNA: EEF; related)

- https://github.com/mtrudel/bandit/commit/bb407f2277dcb65a58dd8cc07913a0b58a80e266 (CNA: EEF; related)

- https://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a (CNA: EEF; patch)

- https://github.com/mtrudel/bandit/security/advisories/GHSA-2v5v-8f9v-xh85 (ADP: CISA-ADP; exploit)

- https://cna.erlef.org/cves/CVE-2026-110314.html (6b3ad84c-e1a6-4bf7-a703-f496b71e49db)

- https://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a (6b3ad84c-e1a6-4bf7-a703-f496b71e49db)

- https://github.com/mtrudel/bandit/commit/bb407f2277dcb65a58dd8cc07913a0b58a80e266 (6b3ad84c-e1a6-4bf7-a703-f496b71e49db)

- https://github.com/mtrudel/bandit/security/advisories/GHSA-2v5v-8f9v-xh85 (6b3ad84c-e1a6-4bf7-a703-f496b71e49db)

- https://osv.dev/vulnerability/EEF-CVE-2026-110314 (6b3ad84c-e1a6-4bf7-a703-f496b71e49db)

- https://github.com/mtrudel/bandit/security/advisories/GHSA-2v5v-8f9v-xh85 (134c704f-9b21-4f2e-91b3-4a467353bcc0)

## Provenance

- CNA: EEF: https://www.cve.org/CVERecord?id=CVE-2026-110314; retrieved 2026-11-02; source updated 2026-11-02

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-110314; retrieved 2026-11-03; source updated 2026-11-02

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-110314; retrieved 2026-11-02; source updated Not reported

Revision: 6d70f6193c5316ecc8590143c55627650da717ae59f5ec3282a91d54f7884d7f

Canonical: https://y2.dev/cve/CVE-2026-110314

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