Vulnerability-Lookup

CVE-2026-84382 (GCVE-0-2026-84382)

Vulnerability from cvelistv5 – Published: 2026-09-02 18:03 – Updated: 2026-09-03 14:31

Title

HTTPX2: Streaming response decompression does not bound peak memory (decompression amplification)

Summary

HTTPX2 is a next generation HTTP client for Python. Prior to 2.12.0, the HTTPX2 content decoders in src/httpx2/httpx2/_decoders.py fully inflate each gzip, deflate, br, or zstd network chunk before iter_bytes() or aiter_bytes() yields bounded pieces to the application. A 64 KiB compressed chunk can expand to approximately 64 MiB in one intermediate allocation, so an attacker-controlled or compromised server can cause severe memory pressure or out-of-memory process termination even when the application streams the response. This issue is fixed in version 2.12.0.

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-03 14:09 UTC

CWE

CWE-409 - Improper Handling of Highly Compressed Data (Data Amplification)

Assigner

GitHub_M mitre root

References

4 references

URL	Tags
https://github.com/pydantic/httpx2/security/advis…	x_refsource_CONFIRM
https://github.com/pydantic/httpx2/pull/1126	x_refsource_MISC
https://github.com/pydantic/httpx2/commit/4fd0c70…	x_refsource_MISC
https://github.com/pydantic/httpx2/releases/tag/v2.12.0	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
pydantic	httpx2	Affected: < 2.12.0	guessed

Show details on NVD website

JSON

To clipboard

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                "id": "CVE-2026-84382",
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FKIE_CVE-2026-84382

Vulnerability from fkie_nvd - Published: 2026-09-02 19:18 - Updated: 2026-09-09 21:05

Severity

7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/pydantic/httpx2/commit/4fd0c70a3f207c618b145934792f791bccfb39f8
	security-advisories@github.com	https://github.com/pydantic/httpx2/pull/1126
	security-advisories@github.com	https://github.com/pydantic/httpx2/releases/tag/v2.12.0
	security-advisories@github.com	https://github.com/pydantic/httpx2/security/advisories/GHSA-8xx6-hgc6-gc2m

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "httpx2",
          "vendor": "pydantic",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.12.0"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "HTTPX2 is a next generation HTTP client for Python. Prior to 2.12.0, the HTTPX2 content decoders in src/httpx2/httpx2/_decoders.py fully inflate each gzip, deflate, br, or zstd network chunk before iter_bytes() or aiter_bytes() yields bounded pieces to the application. A 64 KiB compressed chunk can expand to approximately 64 MiB in one intermediate allocation, so an attacker-controlled or compromised server can cause severe memory pressure or out-of-memory process termination even when the application streams the response. This issue is fixed in version 2.12.0."
    }
  ],
  "id": "CVE-2026-84382",
  "lastModified": "2026-09-09T21:05:23.237",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
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        "impactScore": 3.6,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
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    "ssvcV203": [
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  "published": "2026-09-02T19:18:08.353",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/pydantic/httpx2/commit/4fd0c70a3f207c618b145934792f791bccfb39f8"
    },
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    }
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}

GHSA-8XX6-HGC6-GC2M

Vulnerability from github – Published: 2026-09-08 20:48 – Updated: 2026-09-08 20:48

Summary

HTTPX2: Streaming response decompression does not bound peak memory (decompression amplification)

Details

Summary

When decoding a compressed response body (gzip, deflate, br, or zstd), HTTPX2 fully decompressed each network read before yielding content to the application. A small compressed input could therefore cause a large intermediate memory allocation, even when the application streamed the response to keep memory usage bounded.

Details

HTTPX2's default transport reads the socket in pieces of up to 64 KiB. Before 2.12.0, each piece was inflated completely into one intermediate allocation before any decompressed bytes were yielded.

At DEFLATE's maximum compression ratio of roughly 1032:1, a 64 KiB compressed chunk can expand to about 64 MiB in one allocation. Brotli and Zstandard responses can cause similarly large amplification. Streaming the response did not prevent these transient allocations.

Impact

Applications that fetch resources from untrusted or attacker-influenced servers - such as webhook receivers, link unfurlers, crawlers, SSRF-reachable fetchers, and redirect followers - can experience memory pressure or out-of-memory termination when processing a malicious compressed response. No authentication or user interaction is required beyond issuing a request to the server.

Mitigation

Upgrade to HTTPX2 2.12.0 or later. Patched versions decompress responses incrementally with bounded intermediate buffers, including responses with multiple content encodings.

Severity

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "httpx2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.12.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-84382"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-409"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-08T20:48:59Z",
    "nvd_published_at": "2026-09-02T19:18:08Z",
    "severity": "HIGH"
  },
  "details": "### Summary\n\nWhen decoding a compressed response body (`gzip`, `deflate`, `br`, or `zstd`), HTTPX2 fully decompressed each network read before yielding content to the application. A small compressed input could therefore cause a large intermediate memory allocation, even when the application streamed the response to keep memory usage bounded.\n\n### Details\n\nHTTPX2\u0027s default transport reads the socket in pieces of up to 64 KiB. Before `2.12.0`, each piece was inflated completely into one intermediate allocation before any decompressed bytes were yielded.\n\nAt DEFLATE\u0027s maximum compression ratio of roughly 1032:1, a 64 KiB compressed chunk can expand to about 64 MiB in one allocation. Brotli and Zstandard responses can cause similarly large amplification. Streaming the response did not prevent these transient allocations.\n\n### Impact\n\nApplications that fetch resources from untrusted or attacker-influenced servers - such as webhook receivers, link unfurlers, crawlers, SSRF-reachable fetchers, and redirect followers - can experience memory pressure or out-of-memory termination when processing a malicious compressed response. No authentication or user interaction is required beyond issuing a request to the server.\n\n### Mitigation\n\nUpgrade to HTTPX2 `2.12.0` or later. Patched versions decompress responses incrementally with bounded intermediate buffers, including responses with multiple content encodings.",
  "id": "GHSA-8xx6-hgc6-gc2m",
  "modified": "2026-09-08T20:48:59Z",
  "published": "2026-09-08T20:48:59Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pydantic/httpx2/security/advisories/GHSA-8xx6-hgc6-gc2m"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-84382"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pydantic/httpx2/pull/1126"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pydantic/httpx2/commit/4fd0c70a3f207c618b145934792f791bccfb39f8"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/pydantic/httpx2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pydantic/httpx2/releases/tag/v2.12.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "HTTPX2: Streaming response decompression does not bound peak memory (decompression amplification)"
}

PYSEC-2026-3846

Vulnerability from pysec - Published: 2026-09-10 09:45 - Updated: 2026-09-10 11:02

Details

Summary

Details

HTTPX2's default transport reads the socket in pieces of up to 64 KiB. Before 2.12.0, each piece was inflated completely into one intermediate allocation before any decompressed bytes were yielded.

Impact

Mitigation

Upgrade to HTTPX2 2.12.0 or later. Patched versions decompress responses incrementally with bounded intermediate buffers, including responses with multiple content encodings.

Severity

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Impacted products

Name	purl
httpx2	pkg:pypi/httpx2

Aliases

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "httpx2",
        "purl": "pkg:pypi/httpx2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.12.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.0.0",
        "2.0.0",
        "2.0.0b1",
        "2.1.0",
        "2.10.0",
        "2.11.0",
        "2.2.0",
        "2.3.0",
        "2.4.0",
        "2.5.0",
        "2.6.0",
        "2.7.0",
        "2.8.0",
        "2.9.0",
        "2.9.1"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-84382",
    "GHSA-8xx6-hgc6-gc2m"
  ],
  "details": "### Summary\n\nWhen decoding a compressed response body (`gzip`, `deflate`, `br`, or `zstd`), HTTPX2 fully decompressed each network read before yielding content to the application. A small compressed input could therefore cause a large intermediate memory allocation, even when the application streamed the response to keep memory usage bounded.\n\n### Details\n\nHTTPX2\u0027s default transport reads the socket in pieces of up to 64 KiB. Before `2.12.0`, each piece was inflated completely into one intermediate allocation before any decompressed bytes were yielded.\n\nAt DEFLATE\u0027s maximum compression ratio of roughly 1032:1, a 64 KiB compressed chunk can expand to about 64 MiB in one allocation. Brotli and Zstandard responses can cause similarly large amplification. Streaming the response did not prevent these transient allocations.\n\n### Impact\n\nApplications that fetch resources from untrusted or attacker-influenced servers - such as webhook receivers, link unfurlers, crawlers, SSRF-reachable fetchers, and redirect followers - can experience memory pressure or out-of-memory termination when processing a malicious compressed response. No authentication or user interaction is required beyond issuing a request to the server.\n\n### Mitigation\n\nUpgrade to HTTPX2 `2.12.0` or later. Patched versions decompress responses incrementally with bounded intermediate buffers, including responses with multiple content encodings.",
  "id": "PYSEC-2026-3846",
  "modified": "2026-09-10T11:02:09.316285Z",
  "published": "2026-09-10T09:45:01.110644Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pydantic/httpx2/security/advisories/GHSA-8xx6-hgc6-gc2m"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-84382"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pydantic/httpx2/pull/1126"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pydantic/httpx2/commit/4fd0c70a3f207c618b145934792f791bccfb39f8"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/pydantic/httpx2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pydantic/httpx2/releases/tag/v2.12.0"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/httpx2"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-8xx6-hgc6-gc2m"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "HTTPX2: Streaming response decompression does not bound peak memory (decompression amplification)"
}

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.

Detection rules are retrieved from Rulezet.

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.

Action not permitted

CVE-2026-84382 (GCVE-0-2026-84382)

FKIE_CVE-2026-84382

GHSA-8XX6-HGC6-GC2M

Summary

Details

Impact

Mitigation

PYSEC-2026-3846

Summary

Details

Impact

Mitigation

Tags

Sightings

Nomenclature