HTTP/1.1 chunked request bodies made of 1-byte chunks amplify memory use in Bandit
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 1.14.0
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: yes
- Technical impact: partial
Summary
Bandit, an Elixir-based HTTP server, is affected when it processes HTTP/1.1 requests with chunked bodies made of many tiny chunks. An unauthenticated remote attacker could send such requests to consume large amounts of server memory and CPU, potentially making the server unresponsive.
Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.
Read the original description
Allocation of Resources Without Limits or Throttling vulnerability in the HTTP/1.1 chunked body reader of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory and CPU via a request body made of many 1-byte chunks. The chunked reader in lib/bandit/http1/socket.ex keeps every chunk as its own list cell and binary term until IO.iodata_to_binary/1 joins them, and nothing limits the number of chunks. The :length option of read_body/2 counts only data bytes, so tiny chunks cost far more memory than their payload: 48 MB of 1-byte chunks grew one handler process to about 500 MB and took about 6 s of CPU. The route does not need to read the body, because on keep-alive connections ensure_completed/1 drains unread bodies through the same reader. This issue affects bandit: from 0.1.0 before 1.14.0.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: yes · Technical impact: partial
- Record last updated
Affected versions
- bandit
From 0.1.0 · fixed in 1.14.0
- mtrudel/bandit
From 7201270c34b90f6c9e15c0386c2bb802c0c72ab4 · fixed in 220b9dfd27f9a21305be2afc75cbe585ddc24e7a