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4 vulnerabilities by wojtekmach
CVE-2026-49756 (GCVE-0-2026-49756)
Vulnerability from nvd – Published: 2026-06-08 15:20 – Updated: 2026-06-08 16:34
VLAI
Title
Multipart form-data header injection in Req via unescaped name/filename/content_type
Summary
Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability in wojtekmach Req allows multipart parameter smuggling via attacker-influenced part metadata.
Req.Utils.encode_form_part/2 in lib/req/utils.ex builds the per-part headers by interpolating the caller-supplied name, filename, and content_type values directly into the content-disposition and content-type lines with no escaping or CRLF stripping. A value containing ", \r, or \n closes the surrounding quoted value and starts a new header line; an additional \r\n--<boundary> terminates the current part and prepends a smuggled part of the attacker's choosing.
This is reachable through every supported way of supplying a part. It is particularly easy when value is a %File.Stream{}, because filename then defaults to Path.basename(stream.path) and POSIX filenames may legitimately contain \r and \n. Any application that forwards user-controlled filenames (or field names / MIME types) through Req.post/2 with form_multipart: lets an attacker inject arbitrary headers into the outgoing multipart body or smuggle additional fields and parts into the request the victim service sends downstream.
This issue affects req: from 0.5.3 before 0.6.0.
Severity
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-93 - Improper Neutralization of CRLF Sequences ('CRLF Injection')
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/wojtekmach/req/security/adviso… | vendor-advisoryrelated |
| https://cna.erlef.org/cves/CVE-2026-49756.html | related |
| https://osv.dev/vulnerability/EEF-CVE-2026-49756 | related |
| https://github.com/wojtekmach/req/commit/74506ff2… | patch |
Impacted products
2 products
| Vendor | Product | Version | |
|---|---|---|---|
| wojtekmach | req |
Affected:
0.5.3 , < 0.6.0
(semver)
cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:* |
|
| wojtekmach | req |
Affected:
60253dbe9436cb8e9c738f895032f2e87939b597 , < 74506ff2c5addf74df85d79dc726e9b2e264a8ba
(git)
cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:* |
Credits
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CVE-2026-49755 (GCVE-0-2026-49755)
Vulnerability from nvd – Published: 2026-06-08 15:20 – Updated: 2026-06-08 17:14
VLAI
Title
Decompression bomb DoS in Req via auto-decoded archive and compressed response bodies
Summary
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.
Req'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. Each returns the full decompressed archive contents as a [{name, bytes}] list in memory, with no per-entry or total size cap. decompress_body/1 walks the content-encoding header and chains :zlib/:brotli/:ezstd decoders, so a response advertising content-encoding: gzip, gzip, gzip inflates through multiple layers without bound.
Both steps are enabled by default, no caller opt-in is required, and the attacker controls the content-type and content-encoding 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.
This issue affects req: from 0.1.0 before 0.6.1.
Severity
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-409 - Improper Handling of Highly Compressed Data (Data Amplification)
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/wojtekmach/req/security/adviso… | vendor-advisoryrelated |
| https://cna.erlef.org/cves/CVE-2026-49755.html | related |
| https://osv.dev/vulnerability/EEF-CVE-2026-49755 | related |
| https://github.com/wojtekmach/req/commit/84977e5b… | patch |
Impacted products
2 products
| Vendor | Product | Version | |
|---|---|---|---|
| wojtekmach | req |
Affected:
0.1.0 , < 0.6.1
(semver)
cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:* |
|
| wojtekmach | req |
Affected:
e37753741cbdc725e6aba3d977b380163bfc0ecb , < 84977e5b1a83f26e749d55ad06e3625464af4e8d
(git)
cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:* |
Credits
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CVE-2026-49755 (GCVE-0-2026-49755)
Vulnerability from cvelistv5 – Published: 2026-06-08 15:20 – Updated: 2026-06-08 17:14
VLAI
Title
Decompression bomb DoS in Req via auto-decoded archive and compressed response bodies
Summary
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.
Req'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. Each returns the full decompressed archive contents as a [{name, bytes}] list in memory, with no per-entry or total size cap. decompress_body/1 walks the content-encoding header and chains :zlib/:brotli/:ezstd decoders, so a response advertising content-encoding: gzip, gzip, gzip inflates through multiple layers without bound.
Both steps are enabled by default, no caller opt-in is required, and the attacker controls the content-type and content-encoding 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.
This issue affects req: from 0.1.0 before 0.6.1.
Severity
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-409 - Improper Handling of Highly Compressed Data (Data Amplification)
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/wojtekmach/req/security/adviso… | vendor-advisoryrelated |
| https://cna.erlef.org/cves/CVE-2026-49755.html | related |
| https://osv.dev/vulnerability/EEF-CVE-2026-49755 | related |
| https://github.com/wojtekmach/req/commit/84977e5b… | patch |
Impacted products
2 products
| Vendor | Product | Version | |
|---|---|---|---|
| wojtekmach | req |
Affected:
0.1.0 , < 0.6.1
(semver)
cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:* |
|
| wojtekmach | req |
Affected:
e37753741cbdc725e6aba3d977b380163bfc0ecb , < 84977e5b1a83f26e749d55ad06e3625464af4e8d
(git)
cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:* |
Credits
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CVE-2026-49756 (GCVE-0-2026-49756)
Vulnerability from cvelistv5 – Published: 2026-06-08 15:20 – Updated: 2026-06-08 16:34
VLAI
Title
Multipart form-data header injection in Req via unescaped name/filename/content_type
Summary
Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability in wojtekmach Req allows multipart parameter smuggling via attacker-influenced part metadata.
Req.Utils.encode_form_part/2 in lib/req/utils.ex builds the per-part headers by interpolating the caller-supplied name, filename, and content_type values directly into the content-disposition and content-type lines with no escaping or CRLF stripping. A value containing ", \r, or \n closes the surrounding quoted value and starts a new header line; an additional \r\n--<boundary> terminates the current part and prepends a smuggled part of the attacker's choosing.
This is reachable through every supported way of supplying a part. It is particularly easy when value is a %File.Stream{}, because filename then defaults to Path.basename(stream.path) and POSIX filenames may legitimately contain \r and \n. Any application that forwards user-controlled filenames (or field names / MIME types) through Req.post/2 with form_multipart: lets an attacker inject arbitrary headers into the outgoing multipart body or smuggle additional fields and parts into the request the victim service sends downstream.
This issue affects req: from 0.5.3 before 0.6.0.
Severity
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-93 - Improper Neutralization of CRLF Sequences ('CRLF Injection')
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/wojtekmach/req/security/adviso… | vendor-advisoryrelated |
| https://cna.erlef.org/cves/CVE-2026-49756.html | related |
| https://osv.dev/vulnerability/EEF-CVE-2026-49756 | related |
| https://github.com/wojtekmach/req/commit/74506ff2… | patch |
Impacted products
2 products
| Vendor | Product | Version | |
|---|---|---|---|
| wojtekmach | req |
Affected:
0.5.3 , < 0.6.0
(semver)
cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:* |
|
| wojtekmach | req |
Affected:
60253dbe9436cb8e9c738f895032f2e87939b597 , < 74506ff2c5addf74df85d79dc726e9b2e264a8ba
(git)
cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:* |
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"packageURL": "pkg:github/wojtekmach/req",
"product": "req",
"programFiles": [
"lib/req/utils.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.Req.Utils\u0027:encode_form_part/2"
}
],
"repo": "https://github.com/wojtekmach/req.git",
"vendor": "wojtekmach",
"versions": [
{
"lessThan": "74506ff2c5addf74df85d79dc726e9b2e264a8ba",
"status": "affected",
"version": "60253dbe9436cb8e9c738f895032f2e87939b597",
"versionType": "git"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:*",
"versionEndExcluding": "0.6.0",
"versionStartIncluding": "0.5.3",
"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 Neutralization of CRLF Sequences (\u0027CRLF Injection\u0027) vulnerability in wojtekmach Req allows multipart parameter smuggling via attacker-influenced part metadata.\u003cp\u003e\u003ctt\u003e\u0027Elixir.Req.Utils\u0027:encode_form_part/2\u003c/tt\u003e in \u003ctt\u003elib/req/utils.ex\u003c/tt\u003e builds the per-part headers by interpolating the caller-supplied \u003ctt\u003ename\u003c/tt\u003e, \u003ctt\u003efilename\u003c/tt\u003e, and \u003ctt\u003econtent_type\u003c/tt\u003e values directly into the \u003ctt\u003econtent-disposition\u003c/tt\u003e and \u003ctt\u003econtent-type\u003c/tt\u003e lines with no escaping or CRLF stripping. A value containing \u003ctt\u003e\"\u003c/tt\u003e, \u003ctt\u003e\\r\u003c/tt\u003e, or \u003ctt\u003e\\n\u003c/tt\u003e closes the surrounding quoted value and starts a new header line; an additional \u003ctt\u003e\\r\\n--\u0026lt;boundary\u0026gt;\u003c/tt\u003e terminates the current part and prepends a smuggled part of the attacker\u0027s choosing.\u003c/p\u003e\u003cp\u003eThis is reachable through every supported way of supplying a part. It is particularly easy when \u003ctt\u003evalue\u003c/tt\u003e is a \u003ctt\u003e%File.Stream{}\u003c/tt\u003e, because \u003ctt\u003efilename\u003c/tt\u003e then defaults to \u003ctt\u003ePath.basename(stream.path)\u003c/tt\u003e and POSIX filenames may legitimately contain \u003ctt\u003e\\r\u003c/tt\u003e and \u003ctt\u003e\\n\u003c/tt\u003e. Any application that forwards user-controlled filenames (or field names / MIME types) through \u003ctt\u003e\u0027Elixir.Req\u0027:post/2\u003c/tt\u003e with \u003ctt\u003eform_multipart:\u003c/tt\u003e lets an attacker inject arbitrary headers into the outgoing multipart body or smuggle additional fields and parts into the request the victim service sends downstream.\u003c/p\u003e\u003cp\u003eThis issue affects req: from 0.5.3 before 0.6.0.\u003c/p\u003e"
}
],
"value": "Improper Neutralization of CRLF Sequences (\u0027CRLF Injection\u0027) vulnerability in wojtekmach Req allows multipart parameter smuggling via attacker-influenced part metadata.\n\nReq.Utils.encode_form_part/2 in lib/req/utils.ex builds the per-part headers by interpolating the caller-supplied name, filename, and content_type values directly into the content-disposition and content-type lines with no escaping or CRLF stripping. A value containing \", \\r, or \\n closes the surrounding quoted value and starts a new header line; an additional \\r\\n--\u003cboundary\u003e terminates the current part and prepends a smuggled part of the attacker\u0027s choosing.\n\nThis is reachable through every supported way of supplying a part. It is particularly easy when value is a %File.Stream{}, because filename then defaults to Path.basename(stream.path) and POSIX filenames may legitimately contain \\r and \\n. Any application that forwards user-controlled filenames (or field names / MIME types) through Req.post/2 with form_multipart: lets an attacker inject arbitrary headers into the outgoing multipart body or smuggle additional fields and parts into the request the victim service sends downstream.\n\nThis issue affects req: from 0.5.3 before 0.6.0."
}
],
"impacts": [
{
"capecId": "CAPEC-33",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-33 HTTP Request Smuggling"
}
]
},
{
"capecId": "CAPEC-105",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-105 HTTP Request Splitting"
}
]
}
],
"metrics": [
{
"cvssV4_0": {
"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "LOCAL",
"baseScore": 2.1,
"baseSeverity": "LOW",
"privilegesRequired": "NONE",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "LOW",
"subIntegrityImpact": "LOW",
"userInteraction": "NONE",
"vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "NONE",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "LOW"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-93",
"description": "CWE-93 Improper Neutralization of CRLF Sequences (\u0027CRLF Injection\u0027)",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-06-08T16:34:58.505Z",
"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"shortName": "EEF"
},
"references": [
{
"tags": [
"vendor-advisory",
"related"
],
"url": "https://github.com/wojtekmach/req/security/advisories/GHSA-px9f-whj3-246m"
},
{
"tags": [
"related"
],
"url": "https://cna.erlef.org/cves/CVE-2026-49756.html"
},
{
"tags": [
"related"
],
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-49756"
},
{
"tags": [
"patch"
],
"url": "https://github.com/wojtekmach/req/commit/74506ff2c5addf74df85d79dc726e9b2e264a8ba"
}
],
"source": {
"discovery": "EXTERNAL"
},
"title": "Multipart form-data header injection in Req via unescaped name/filename/content_type",
"workarounds": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eSanitize attacker-influenced \u003ctt\u003ename\u003c/tt\u003e, \u003ctt\u003efilename\u003c/tt\u003e, and \u003ctt\u003econtent_type\u003c/tt\u003e values before passing them to \u003ctt\u003e\u0027Elixir.Req\u0027:post/2\u003c/tt\u003e with \u003ctt\u003eform_multipart:\u003c/tt\u003e. At minimum, reject (or strip) any value containing \u003ctt\u003e\\r\u003c/tt\u003e, \u003ctt\u003e\\n\u003c/tt\u003e, or \u003ctt\u003e\"\u003c/tt\u003e. When forwarding uploads, derive \u003ctt\u003efilename\u003c/tt\u003e from a normalised string rather than \u003ctt\u003ePath.basename/1\u003c/tt\u003e on a user-controlled path.\u003c/p\u003e"
}
],
"value": "Sanitize attacker-influenced name, filename, and content_type values before passing them to Req.post/2 with form_multipart:. At minimum, reject (or strip) any value containing \\r, \\n, or \". When forwarding uploads, derive filename from a normalised string rather than Path.basename/1 on a user-controlled path."
}
],
"x_generator": {
"engine": "cvelib 1.8.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"assignerShortName": "EEF",
"cveId": "CVE-2026-49756",
"datePublished": "2026-06-08T15:20:24.035Z",
"dateReserved": "2026-06-01T13:45:22.448Z",
"dateUpdated": "2026-06-08T16:34:58.505Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}