Quadratic bignum parsing of Content-Length and Host port values 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- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean?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 web server for HTTP/1 and HTTP/2, is affected through its header integer parsing used for Content-Length and Host or :authority port values. An unauthenticated remote attacker can send oversized numeric header values, causing the server to consume excessive CPU time and degrade availability.
Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.
Read the original description
Inefficient Algorithmic Complexity vulnerability in the header integer parser of mtrudel bandit allows an unauthenticated remote attacker to consume server CPU via a content-length value or a Host or :authority port made of thousands of digits. Bandit.Headers.parse_integer/2 in lib/bandit/headers.ex builds the number one digit at a time with no limit on the digit count, allocating a new bignum at each step, so one value costs time quadratic in its length. It runs on raw request input over HTTP/1 and HTTP/2, before any range check. Over HTTP/2, a 4,000-digit value can be stored once in the HPACK dynamic table and re-sent on each new stream for about one byte: 124 KB of traffic kept the server busy for 27.9 s. This issue affects bandit: from 1.0.0-pre.7 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 1.0.0-pre.7 · fixed in 1.14.0
- mtrudel/bandit
From e0c8c0c30af9b0f57d8aafac37ddd9294363a8be · fixed in 220b9dfd27f9a21305be2afc75cbe585ddc24e7a