{"containers":{"cna":{"affected":[{"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","modules":["'Elixir.Bandit.HTTP1.Socket'"],"packageName":"bandit","packageURL":"pkg:hex/bandit","product":"bandit","programFiles":["lib/bandit/http1/socket.ex"],"programRoutines":[{"name":"'Elixir.Bandit.HTTP1.Socket':read_data/2"},{"name":"'Elixir.Bandit.HTTP1.Socket':do_read_chunked_data!/5"}],"repo":"https://github.com/mtrudel/bandit","vendor":"mtrudel","versions":[{"lessThan":"1.11.1","status":"affected","version":"1.4.0","versionType":"semver"}]},{"collectionURL":"https://github.com","cpes":["cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","modules":["'Elixir.Bandit.HTTP1.Socket'"],"packageName":"mtrudel/bandit","packageURL":"pkg:github/mtrudel/bandit","product":"bandit","programFiles":["lib/bandit/http1/socket.ex"],"programRoutines":[{"name":"'Elixir.Bandit.HTTP1.Socket':read_data/2"},{"name":"'Elixir.Bandit.HTTP1.Socket':do_read_chunked_data!/5"}],"repo":"https://github.com/mtrudel/bandit","vendor":"mtrudel","versions":[{"lessThan":"ae3520dfdbfab115c638f8c7f6f6b805db34e1ab","status":"affected","version":"903e209a521bc216b9f9065c01ae9a0cac2d5a10","versionType":"git"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*","versionEndExcluding":"1.11.1","versionStartIncluding":"1.4.0","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"AND"}],"credits":[{"lang":"en","type":"finder","value":"Peter Ullrich"},{"lang":"en","type":"remediation developer","value":"Mat Trudel"},{"lang":"en","type":"analyst","value":"Jonatan Männchen"}],"descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion.<p>The chunked clause of <tt>'Elixir.Bandit.HTTP1.Socket':read_data/2</tt> in <tt>lib/bandit/http1/socket.ex</tt> ignores the caller-supplied <tt>:length</tt> option when reading HTTP/1 chunked request bodies. Instead of capping the accumulated body at the configured limit (e.g. <tt>Plug.Parsers</tt>' default 8 MB), <tt>do_read_chunked_data!/5</tt> buffers every received chunk into an iolist unconditionally and materializes the entire body as a single binary. The function always returns <tt>{:ok, body, ...}</tt>, so callers cannot interpose a 413 response.</p><p>Because <tt>Plug.Parsers</tt> runs before routing and authentication in the standard Phoenix endpoint, an unauthenticated attacker needs no valid route or credentials. Sending a single <tt>Transfer-Encoding: chunked</tt> POST request with an arbitrarily large body to any path causes the BEAM process to exhaust available memory and be terminated by the OS OOM killer.</p><p>The content-length path in the same function correctly enforces the limit and is not affected.</p><p>This issue affects bandit: from 1.4.0 before 1.11.1.</p>"}],"value":"Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion.\n\nThe chunked clause of 'Elixir.Bandit.HTTP1.Socket':read_data/2 in lib/bandit/http1/socket.ex ignores the caller-supplied :length option when reading HTTP/1 chunked request bodies. Instead of capping the accumulated body at the configured limit (e.g. Plug.Parsers' default 8 MB), do_read_chunked_data!/5 buffers every received chunk into an iolist unconditionally and materializes the entire body as a single binary. The function always returns {:ok, body, ...}, so callers cannot interpose a 413 response.\n\nBecause Plug.Parsers runs before routing and authentication in the standard Phoenix endpoint, an unauthenticated attacker needs no valid route or credentials. Sending a single Transfer-Encoding: chunked POST request with an arbitrarily large body to any path causes the BEAM process to exhaust available memory and be terminated by the OS OOM killer.\n\nThe content-length path in the same function correctly enforces the limit and is not affected.\n\nThis issue affects bandit: from 1.4.0 before 1.11.1."}],"impacts":[{"capecId":"CAPEC-130","descriptions":[{"lang":"en","value":"CAPEC-130 Excessive Allocation"}]}],"metrics":[{"cvssV4_0":{"attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":8.7,"baseSeverity":"HIGH","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-770","description":"CWE-770 Allocation of Resources Without Limits or Throttling","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-05-13T13:48:03.371Z","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","shortName":"EEF"},"references":[{"tags":["vendor-advisory","related"],"url":"https://github.com/mtrudel/bandit/security/advisories/GHSA-9q9q-324x-93r2"},{"tags":["related"],"url":"https://cna.erlef.org/cves/CVE-2026-39803.html"},{"tags":["related"],"url":"https://osv.dev/vulnerability/EEF-CVE-2026-39803"},{"tags":["patch"],"url":"https://github.com/mtrudel/bandit/commit/ae3520dfdbfab115c638f8c7f6f6b805db34e1ab"}],"source":{"discovery":"EXTERNAL"},"title":"HTTP/1 chunked body reader ignores length cap in bandit","x_generator":{"engine":"cvelib 1.8.0"}}},"cveMetadata":{"assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","assignerShortName":"EEF","cveId":"CVE-2026-39803","datePublished":"2026-05-13T13:36:09.648Z","dateReserved":"2026-04-07T12:28:54.916Z","dateUpdated":"2026-05-13T13:48:03.371Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"}