Vulnerability · Published Oct 26, 2026 · Assigned by EEF
CVE-2026-111101HTTP/1.1 chunked request bodies made of 1-byte chunks amplify memory use in Bandit
High 8.7
In plain English
A high-severity resource allocation without limits in bandit from mtrudel. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 49% of all known vulnerabilities).
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu:22.04:LTS | bandit | no fix listed | UBUNTU-CVE-2026-111101 |
| Ubuntu:24.04:LTS | bandit | no fix listed | UBUNTU-CVE-2026-111101 |
| Ubuntu:26.04:LTS | bandit | no fix listed | UBUNTU-CVE-2026-111101 |
| Ubuntu:26.10 | bandit | no fix listed | UBUNTU-CVE-2026-111101 |
Affected products (as reported)
Weakness: CWE-770 · 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