CVE-2026-84380 (GCVE-0-2026-84380)
Vulnerability from cvelistv5 – Published: 2026-09-02 17:58 – Updated: 2026-09-02 18:07
VLAI
EPSS
VEX
Title
HTTPX2: Conflicting Content-Length and Transfer-Encoding headers can be auto-generated
Summary
HTTPX2 is a next generation HTTP client for Python. Prior to 2.11.0, Request._prepare() in src/httpx2/httpx2/_models.py can add a body-derived Content-Length header to a request that already contains a caller-supplied Transfer-Encoding header because its setdefault() processing checks each default header independently rather than treating the two framing headers as mutually exclusive. Fixed-size byte, JSON, form, and known-length multipart bodies can therefore be serialized over HTTP/1.1 with both headers, allowing request smuggling or connection desynchronization when downstream intermediaries disagree about which framing header takes precedence. This issue is fixed in version 2.11.0.
Severity
5.6 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-02 18:07 UTC
CWE
- CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/pydantic/httpx2/security/advis… | x_refsource_CONFIRM |
| https://github.com/pydantic/httpx2/pull/1137 | x_refsource_MISC |
| https://github.com/pydantic/httpx2/commit/829b93a… | x_refsource_MISC |
| https://github.com/pydantic/httpx2/releases/tag/v2.11.0 | x_refsource_MISC |
Impacted products
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-84380",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-09-02T18:07:09.850518Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-09-02T18:07:36.980Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"product": "httpx2",
"vendor": "pydantic",
"versions": [
{
"status": "affected",
"version": "\u003c 2.11.0"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "HTTPX2 is a next generation HTTP client for Python. Prior to 2.11.0, Request._prepare() in src/httpx2/httpx2/_models.py can add a body-derived Content-Length header to a request that already contains a caller-supplied Transfer-Encoding header because its setdefault() processing checks each default header independently rather than treating the two framing headers as mutually exclusive. Fixed-size byte, JSON, form, and known-length multipart bodies can therefore be serialized over HTTP/1.1 with both headers, allowing request smuggling or connection desynchronization when downstream intermediaries disagree about which framing header takes precedence. This issue is fixed in version 2.11.0."
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "HIGH",
"attackVector": "NETWORK",
"availabilityImpact": "LOW",
"baseScore": 5.6,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "LOW",
"integrityImpact": "LOW",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L",
"version": "3.1"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-444",
"description": "CWE-444: Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027)",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-09-02T17:58:55.520Z",
"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"shortName": "GitHub_M"
},
"references": [
{
"name": "https://github.com/pydantic/httpx2/security/advisories/GHSA-pf96-p4fj-6566",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/pydantic/httpx2/security/advisories/GHSA-pf96-p4fj-6566"
},
{
"name": "https://github.com/pydantic/httpx2/pull/1137",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/pydantic/httpx2/pull/1137"
},
{
"name": "https://github.com/pydantic/httpx2/commit/829b93a2393212996f613e635261f777d9ec6eab",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/pydantic/httpx2/commit/829b93a2393212996f613e635261f777d9ec6eab"
},
{
"name": "https://github.com/pydantic/httpx2/releases/tag/v2.11.0",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/pydantic/httpx2/releases/tag/v2.11.0"
}
],
"source": {
"advisory": "GHSA-pf96-p4fj-6566",
"discovery": "UNKNOWN"
},
"title": "HTTPX2: Conflicting Content-Length and Transfer-Encoding headers can be auto-generated"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-84380",
"datePublished": "2026-09-02T17:58:55.520Z",
"dateReserved": "2026-09-01T16:27:58.130Z",
"dateUpdated": "2026-09-02T18:07:36.980Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-84380",
"date": "2026-09-04",
"epss": "0.00221",
"percentile": "0.1251"
},
"nvd": "{\"cve\":{\"id\":\"CVE-2026-84380\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-09-02T18:21:29.513\",\"lastModified\":\"2026-09-02T19:18:08.113\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"HTTPX2 is a next generation HTTP client for Python. Prior to 2.11.0, Request._prepare() in src/httpx2/httpx2/_models.py can add a body-derived Content-Length header to a request that already contains a caller-supplied Transfer-Encoding header because its setdefault() processing checks each default header independently rather than treating the two framing headers as mutually exclusive. Fixed-size byte, JSON, form, and known-length multipart bodies can therefore be serialized over HTTP/1.1 with both headers, allowing request smuggling or connection desynchronization when downstream intermediaries disagree about which framing header takes precedence. This issue is fixed in version 2.11.0.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"pydantic\",\"product\":\"httpx2\",\"versions\":[{\"version\":\"\u003c 2.11.0\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L\",\"baseScore\":5.6,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"LOW\",\"integrityImpact\":\"LOW\",\"availabilityImpact\":\"LOW\"},\"exploitabilityScore\":2.2,\"impactScore\":3.4}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2026-09-02T18:07:09.850518Z\",\"id\":\"CVE-2026-84380\",\"options\":[{\"exploitation\":\"none\"},{\"automatable\":\"no\"},{\"technicalImpact\":\"partial\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-444\"}]}],\"references\":[{\"url\":\"https://github.com/pydantic/httpx2/commit/829b93a2393212996f613e635261f777d9ec6eab\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/pydantic/httpx2/pull/1137\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/pydantic/httpx2/releases/tag/v2.11.0\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/pydantic/httpx2/security/advisories/GHSA-pf96-p4fj-6566\",\"source\":\"security-advisories@github.com\"}]}}",
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-09-02T19:03:57+00:00",
"cve": "CVE-2026-84380",
"id": "CVE-2026-84380",
"initial_release_date": "2026-09-02T17:58:55.520000+00:00",
"product_status:known_affected": "4",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "httpx2: HTTPX2: Request Smuggling and Connection Desynchronization via Conflicting HTTP Headers",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-84380.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "moderate",
"current_release_date": "2026-09-05T00:24:07Z",
"cve": "CVE-2026-84380",
"id": "CVE-2026-84380",
"initial_release_date": "2026-09-05T00:24:07Z",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-84380",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-84380.json",
"version": "2"
},
"vulnrichment": {
"containers": "{\"cna\": {\"title\": \"HTTPX2: Conflicting Content-Length and Transfer-Encoding headers can be auto-generated\", \"problemTypes\": [{\"descriptions\": [{\"cweId\": \"CWE-444\", \"lang\": \"en\", \"description\": \"CWE-444: Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027)\", \"type\": \"CWE\"}]}], \"metrics\": [{\"cvssV3_1\": {\"attackComplexity\": \"HIGH\", \"attackVector\": \"NETWORK\", \"availabilityImpact\": \"LOW\", \"baseScore\": 5.6, \"baseSeverity\": \"MEDIUM\", \"confidentialityImpact\": \"LOW\", \"integrityImpact\": \"LOW\", \"privilegesRequired\": \"NONE\", \"scope\": \"UNCHANGED\", \"userInteraction\": \"NONE\", \"vectorString\": \"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L\", \"version\": \"3.1\"}}], \"references\": [{\"name\": \"https://github.com/pydantic/httpx2/security/advisories/GHSA-pf96-p4fj-6566\", \"tags\": [\"x_refsource_CONFIRM\"], \"url\": \"https://github.com/pydantic/httpx2/security/advisories/GHSA-pf96-p4fj-6566\"}, {\"name\": \"https://github.com/pydantic/httpx2/pull/1137\", \"tags\": [\"x_refsource_MISC\"], \"url\": \"https://github.com/pydantic/httpx2/pull/1137\"}, {\"name\": \"https://github.com/pydantic/httpx2/commit/829b93a2393212996f613e635261f777d9ec6eab\", \"tags\": [\"x_refsource_MISC\"], \"url\": \"https://github.com/pydantic/httpx2/commit/829b93a2393212996f613e635261f777d9ec6eab\"}, {\"name\": \"https://github.com/pydantic/httpx2/releases/tag/v2.11.0\", \"tags\": [\"x_refsource_MISC\"], \"url\": \"https://github.com/pydantic/httpx2/releases/tag/v2.11.0\"}], \"affected\": [{\"vendor\": \"pydantic\", \"product\": \"httpx2\", \"versions\": [{\"version\": \"\u003c 2.11.0\", \"status\": \"affected\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2026-09-02T17:58:55.520Z\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"HTTPX2 is a next generation HTTP client for Python. Prior to 2.11.0, Request._prepare() in src/httpx2/httpx2/_models.py can add a body-derived Content-Length header to a request that already contains a caller-supplied Transfer-Encoding header because its setdefault() processing checks each default header independently rather than treating the two framing headers as mutually exclusive. Fixed-size byte, JSON, form, and known-length multipart bodies can therefore be serialized over HTTP/1.1 with both headers, allowing request smuggling or connection desynchronization when downstream intermediaries disagree about which framing header takes precedence. This issue is fixed in version 2.11.0.\"}], \"source\": {\"advisory\": \"GHSA-pf96-p4fj-6566\", \"discovery\": \"UNKNOWN\"}}, \"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-84380\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-09-02T18:07:09.850518Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-09-02T18:07:32.081Z\"}}]}",
"cveMetadata": "{\"cveId\": \"CVE-2026-84380\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"state\": \"PUBLISHED\", \"assignerShortName\": \"GitHub_M\", \"dateReserved\": \"2026-09-01T16:27:58.130Z\", \"datePublished\": \"2026-09-02T17:58:55.520Z\", \"dateUpdated\": \"2026-09-02T18:07:36.980Z\"}",
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Loading…
The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Loading…
Loading…