{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-49755", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "state": "PUBLISHED", "assignerShortName": "EEF", "dateReserved": "2026-06-01T13:45:22.448Z", "datePublished": "2026-06-08T15:20:57.415Z", "dateUpdated": "2026-06-08T16:50:03.277Z"}, "containers": {"cna": {"affected": [{"collectionURL": "https://repo.hex.pm", "cpes": ["cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["'Elixir.Req.Steps'"], "packageName": "req", "packageURL": "pkg:hex/req", "product": "req", "programFiles": ["lib/req/steps.ex"], "programRoutines": [{"name": "'Elixir.Req.Steps':decode_body/1"}, {"name": "'Elixir.Req.Steps':decompress_body/1"}], "repo": "https://github.com/wojtekmach/req", "vendor": "wojtekmach", "versions": [{"lessThan": "0.6.1", "status": "affected", "version": "0.1.0", "versionType": "semver"}]}, {"collectionURL": "https://github.com", "cpes": ["cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["'Elixir.Req.Steps'"], "packageName": "wojtekmach/req", "packageURL": "pkg:github/wojtekmach/req", "product": "req", "programFiles": ["lib/req/steps.ex"], "programRoutines": [{"name": "'Elixir.Req.Steps':decode_body/1"}, {"name": "'Elixir.Req.Steps':decompress_body/1"}], "repo": "https://github.com/wojtekmach/req.git", "vendor": "wojtekmach", "versions": [{"lessThan": "84977e5b1a83f26e749d55ad06e3625464af4e8d", "status": "affected", "version": "e37753741cbdc725e6aba3d977b380163bfc0ecb", "versionType": "git"}]}], "cpeApplicability": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:*", "versionEndExcluding": "0.6.1", "versionStartIncluding": "0.1.0", "vulnerable": true}], "negate": false, "operator": "OR"}], "operator": "AND"}], "credits": [{"lang": "en", "type": "finder", "value": "Peter Ullrich"}, {"lang": "en", "type": "remediation developer", "value": "Wojtek Mach"}, {"lang": "en", "type": "analyst", "value": "Jonatan M\u00e4nnchen / EEF"}], "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in wojtekmach Req allows attacker-controlled HTTP servers to exhaust memory in a Req client via decompression-bomb response bodies.<p>Req's default response pipeline includes <tt>'Elixir.Req.Steps':decode_body/1</tt> and <tt>'Elixir.Req.Steps':decompress_body/1</tt> in <tt>lib/req/steps.ex</tt>. <tt>decode_body/1</tt> dispatches on the server-supplied <tt>content-type</tt> (or URL extension) and calls <tt>:zip.extract(body, [:memory])</tt> for <tt>application/zip</tt>, <tt>:erl_tar.extract({:binary, body}, [:memory])</tt> for <tt>application/x-tar</tt>, and <tt>:erl_tar.extract({:binary, body}, [:memory, :compressed])</tt> for <tt>application/gzip</tt> / <tt>.tgz</tt>. Each returns the full decompressed archive contents as a <tt>[{name, bytes}]</tt> list in memory, with no per-entry or total size cap. <tt>decompress_body/1</tt> walks the <tt>content-encoding</tt> header and chains <tt>:zlib</tt>/<tt>:brotli</tt>/<tt>:ezstd</tt> decoders, so a response advertising <tt>content-encoding: gzip, gzip, gzip</tt> inflates through multiple layers without bound.</p><p>Both steps are enabled by default, no caller opt-in is required, and the attacker controls the <tt>content-type</tt> and <tt>content-encoding</tt> headers on their own server (or on any host reached via Req's automatic redirect following). 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A sub-megabyte response can expand to multiple gigabytes on the victim, crashing the BEAM process.\n\nThis issue affects req: from 0.1.0 before 0.6.1."}], "impacts": [{"capecId": "CAPEC-197", "descriptions": [{"lang": "en", "value": "CAPEC-197 Exponential Data Expansion"}]}], "metrics": [{"cvssV4_0": {"attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "baseScore": 8.2, "baseSeverity": "HIGH", "privilegesRequired": "NONE", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/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-409", "description": "CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-06-08T15:20:57.415Z"}, "references": [{"tags": ["vendor-advisory", "related"], "url": "https://github.com/wojtekmach/req/security/advisories/GHSA-655f-mp8p-96gv"}, {"tags": ["related"], "url": "https://cna.erlef.org/cves/CVE-2026-49755.html"}, {"tags": ["related"], "url": "https://osv.dev/vulnerability/EEF-CVE-2026-49755"}, {"tags": ["patch"], "url": "https://github.com/wojtekmach/req/commit/84977e5b1a83f26e749d55ad06e3625464af4e8d"}], "source": {"discovery": "EXTERNAL"}, "title": "Decompression bomb DoS in Req via auto-decoded archive and compressed response bodies", "workarounds": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>Disable Req's automatic body decoding on requests that fetch attacker-influenced URLs by passing <tt>decode_body: false</tt> to <tt>'Elixir.Req':new/1</tt> / <tt>'Elixir.Req':get!/1</tt>. 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Both options leave the response body as the raw on-the-wire bytes, so the caller can size-check before any decompression."}], "x_generator": {"engine": "cvelib 1.8.0"}}, "adp": [{"references": [{"url": "https://github.com/wojtekmach/req/security/advisories/GHSA-655f-mp8p-96gv", "tags": ["exploit"]}], "metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-06-08T16:49:57.977214Z", "id": "CVE-2026-49755", "options": [{"Exploitation": "poc"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-06-08T16:50:03.277Z"}}]}}

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To also skip the content-encoding decompression pipeline, pass raw: true. Both options leave the response body as the raw on-the-wire bytes, so the caller can size-check before any decompression.", "supportingMedia": [{"type": "text/html", "value": "<p>Disable Req's automatic body decoding on requests that fetch attacker-influenced URLs by passing <tt>decode_body: false</tt> to <tt>'Elixir.Req':new/1</tt> / <tt>'Elixir.Req':get!/1</tt>. To also skip the <tt>content-encoding</tt> decompression pipeline, pass <tt>raw: true</tt>. Both options leave the response body as the raw on-the-wire bytes, so the caller can size-check before any decompression.</p>", "base64": false}]}], "x_generator": {"engine": "cvelib 1.8.0"}, "descriptions": [{"lang": "en", "value": "Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in wojtekmach Req allows attacker-controlled HTTP servers to exhaust memory in a Req client via decompression-bomb response bodies.\n\nReq's default response pipeline includes Req.Steps.decode_body/1 and Req.Steps.decompress_body/1 in lib/req/steps.ex. decode_body/1 dispatches on the server-supplied content-type (or URL extension) and calls :zip.extract(body, [:memory]) for application/zip, :erl_tar.extract({:binary, body}, [:memory]) for application/x-tar, and :erl_tar.extract({:binary, body}, [:memory, :compressed]) for application/gzip / .tgz. 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Each returns the full decompressed archive contents as a <tt>[{name, bytes}]</tt> list in memory, with no per-entry or total size cap. <tt>decompress_body/1</tt> walks the <tt>content-encoding</tt> header and chains <tt>:zlib</tt>/<tt>:brotli</tt>/<tt>:ezstd</tt> decoders, so a response advertising <tt>content-encoding: gzip, gzip, gzip</tt> inflates through multiple layers without bound.</p><p>Both steps are enabled by default, no caller opt-in is required, and the attacker controls the <tt>content-type</tt> and <tt>content-encoding</tt> headers on their own server (or on any host reached via Req's automatic redirect following). A sub-megabyte response can expand to multiple gigabytes on the victim, crashing the BEAM process.</p><p>This issue affects req: from 0.1.0 before 0.6.1.</p>", "base64": false}]}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-409", "description": "CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)"}]}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "0.6.1", "versionStartIncluding": "0.1.0"}], "operator": "OR"}], "operator": "AND"}], "providerMetadata": {"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-06-08T15:20:57.415Z"}}}, "cveMetadata": {"cveId": "CVE-2026-49755", "state": "PUBLISHED", "dateUpdated": "2026-06-08T16:50:03.277Z", "dateReserved": "2026-06-01T13:45:22.448Z", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "datePublished": "2026-06-08T15:20:57.415Z", "assignerShortName": "EEF"}, "dataVersion": "5.2"}

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{"created": "2026-06-08T16:45:26.665249+00:00", "updated": "2026-06-08T16:45:26.665266+00:00", "vendors": []}