UBUNTU-CVE-2026-116078: High severity ubuntu/bandit vulnerability
Allocation of Resources Without Limits or Throttling vulnerability in the HTTP/2 request body reader of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory via a request body sent as many 1-byte DATA frames. doreaddata/5 in lib/bandit/http2/stream.ex keeps every DATA frame payload as its own list element until the read returns. The :length option of readbody/2 counts body bytes, not frames, so a body of 1-byte frames costs a list cell and a binary term per byte. Interleaving the frames across up to 500 concurrent streams per connection keeps each stream consuming its frames as they arrive; in the reporter's test, 100 streams held 25 to 40 MiB of stream process memory for 5 MB sent. Only routes whose Plug reads the request body are affected, which includes any route behind Plug.Parsers. This issue affects bandit: from 0.3.1 before 1.14.1.
Affected Software
Frequently Asked Questions
Which applications are exposed to this issue?
Only HTTP/2 routes that read the request body are affected. This includes routes using Plug.Parsers, so applications behind Plug.Parsers should be considered exposed when they accept HTTP/2 requests.
What does an attacker need to do to exploit it?
An unauthenticated remote attacker must send an HTTP/2 request body split into many 1-byte DATA frames. They can interleave frames across up to 500 concurrent streams on a connection to keep stream memory consumption high.
Are default body-size limits sufficient protection?
Not necessarily. The read_body/2 :length option counts body bytes rather than the number of DATA frames, so a request body within the configured byte limit can still consume disproportionate memory when delivered as 1-byte frames.
How can I determine whether the deployed Bandit version is affected?
Bandit versions from 0.3.1 up to, but not including, 1.14.1 are affected. Version 1.14.1 is outside the stated affected range.