What’s Vulnerable › Vulnerabilities

CVE-2026-113436: Quadratic bignum parsing of Content-Length and Host port values in Bandit

• Severity: high (CVSS 8.7 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-26 · updated 2026-10-26
• Weakness: CWE-407

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.

Affected products

• mtrudel bandit: from 1.0.0-pre.7 before 1.14.0 — fixed in 1.14.0

How to fix

Upgrade to a fixed version: mtrudel bandit 1.14.0. Check the vendor advisory for mitigations.

References

• https://cna.erlef.org/cves/CVE-2026-113436.html
• https://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a
• https://github.com/mtrudel/bandit/commit/e0c8c0c30af9b0f57d8aafac37ddd9294363a8be
• https://github.com/mtrudel/bandit/security/advisories/GHSA-29cr-8477-rg6r
• https://osv.dev/vulnerability/EEF-CVE-2026-113436

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