HTTP/2 frames let clients hold Bandit request body reads open
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-770.
Summary
Bandit from 1.4.0 before 1.14.0 has an allocation of resources without limits flaw (CWE-770) in its HTTP/2 request body reader. Stream.do_read_data/4 starts a new full read timeout when a WINDOW_UPDATE or empty SETTINGS frame arrives without body data, so the wait never ends. An unauthenticated remote attacker can keep stream processes and application state blocked for as long as they like by repeatedly sending these frames.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
Allocation of Resources Without Limits or Throttling vulnerability in the HTTP/2 request body reader of mtrudel bandit allows an unauthenticated remote attacker to hold stream processes open indefinitely via WINDOW_UPDATE or empty SETTINGS frames sent while a Plug reads the request body. Bandit.HTTP2.Stream.do_read_data/4 in lib/bandit/http2/stream.ex waits for each frame with a fresh read_timeout. A stream WINDOW_UPDATE, or the zero-delta window update that every empty SETTINGS frame delivers to all streams, ends the wait without delivering any body data, and the loop starts a new full countdown. A client that sends one of these 9-byte frames before each countdown expires keeps read_body blocked, together with the stream process and whatever the application holds while reading, for as long as it likes. This issue affects bandit: from 1.4.0 before 1.14.0.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
Update bandit to version 1.14.0, which fixes the issue. The sources list no advisory identifier for this fix.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA bandit (mtrudel) Fixed in 1.14.0
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
mtrudel bandit 1.14.0, 220b9dfd27f9a21305be2afc75cbe585ddc24e7a
11 records Highest priority Priority MEDIUM 10 MEDIUM, 1 LOW
Other records, highest priority first
- TI-2026-80361 Bandit frames still reach WebSock after server-initiated closePriority MEDIUM 61
- TI-2026-80371 WebSocket 1-byte continuation frames exhaust memory in BanditPriority MEDIUM 45
- TI-2026-80369 Quadratic bignum parsing of Content-Length and Host port values in BanditPriority MEDIUM 45
Timeline
- 2026-10-26 Threatist record created from CVE-2026-115269
- 2026-10-26 CISA SSVC decision points changed
References
More mtrudel vulnerabilities
- TI-2026-81989 HTTP/2 request bodies made of 1-byte DATA frames amplify memory use in Bandit CVSS 4.0HIGH 8.7
- TI-2026-74311 Bandit HTTP/2 send timers reset, letting trickles pin stream processes CVSS 4.0HIGH 8.7
- TI-2026-52571 HTTP/2 connection-window starvation pins Plug processes indefinitely in Bandit CVSS 4.0HIGH 8.7
- TI-2026-46780 Quadratic CPU blow-up reassembling fragmented WebSocket messages in Bandit CVSS 4.0HIGH 8.7
- TI-2026-31007 WebSocket fragmented message reassembly unbounded in bandit CVSS 4.0HIGH 8.7
- TI-2026-28689 HTTP/1 chunked decoder infinite loop on requests with trailer fields in bandit CVSS 4.0HIGH 8.7
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences