Vulnerability-Lookup

CVE-2026-47073 (GCVE-0-2026-47073)

Vulnerability from cvelistv5 – Published: 2026-05-25 14:00 – Updated: 2026-05-27 15:41

Title

Unbounded memory consumption in WebSocket client in hackney

Summary

Allocation of Resources Without Limits or Throttling vulnerability in benoitc hackney allows Flooding. The WebSocket client in src/hackney_ws.erl imposes no upper bound on memory consumption in three code paths. First, read_handshake_response/3 accumulates received bytes into a growing buffer with no size cap; the per-receive timeout resets on every chunk, so a server that streams bytes without ever sending \r\n\r\n causes the buffer to grow until memory is exhausted. Second, parse_payload/9 and parse_active_payload/8 do not validate the declared frame payload length against any limit; because RFC 6455 allows payload lengths up to 2^63-1 bytes, a server that announces a very large frame and dribbles bytes causes the accumulation buffer to grow until OOM. Third, the frag_buffer field in #ws_data{} accumulates continuation frames indefinitely; a server that sends an endless stream of non-final (nofin) fragmented frames without ever sending a final (fin) frame grows frag_buffer without bound. In all three cases the attacker only needs to control the WebSocket server the hackney client connects to, with no authentication or special client configuration required. This issue affects hackney: from 2.0.0 before 4.0.1.

Severity

8.7 (High)


                        
                          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

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-400 - Uncontrolled Resource Consumption

Assigner

EEF

References

4 references

URL	Tags
https://github.com/benoitc/hackney/security/advis…	vendor-advisoryrelated
https://cna.erlef.org/cves/CVE-2026-47073.html	related
https://osv.dev/vulnerability/EEF-CVE-2026-47073	related
https://github.com/benoitc/hackney/commit/ce0109e…	patch

Impacted products

2 products

Vendor	Product	Version
benoitc	hackney	Affected: 2.0.0 , < 4.0.1 (semver) cpe:2.3:a:benoitc:hackney::::::::
benoitc	hackney	Affected: 690cecaf236fba49526da404a5bc889a24367a3e , < ce0109e2970ace6e20ff29bae9d05c3ac22ec6dc (git) cpe:2.3:a:benoitc:hackney::::::::

Credits

Peter Ullrich Benoit Chesneau Jonatan Männchen / EEF

Show details on NVD website

JSON

To clipboard

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    "redhat_vex": {
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      "initial_release_date": "2026-01-01T00:00:00+00:00",
      "product_status:known_not_affected": "1",
      "source": "Red Hat CSAF VEX",
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      "title": "Unbounded memory consumption in WebSocket client in hackney",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-47073.json",
      "version": "3"
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FKIE_CVE-2026-47073

Vulnerability from fkie_nvd - Published: 2026-05-25 15:16 - Updated: 2026-06-17 10:54

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
6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://cna.erlef.org/cves/CVE-2026-47073.html	Patch, Third Party Advisory
6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://github.com/benoitc/hackney/commit/ce0109e2970ace6e20ff29bae9d05c3ac22ec6dc	Patch
6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://github.com/benoitc/hackney/security/advisories/GHSA-q8jg-fgj4-fphf	Exploit, Patch, Vendor Advisory
6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://osv.dev/vulnerability/EEF-CVE-2026-47073	Patch, Third Party Advisory
134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/benoitc/hackney/security/advisories/GHSA-q8jg-fgj4-fphf	Exploit, Patch, Vendor Advisory

Impacted products

	Vendor	Product	Version
	benoitc	hackney	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://repo.hex.pm",
          "cpes": [
            "cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "hackney_ws"
          ],
          "packageName": "hackney",
          "packageURL": "pkg:hex/hackney",
          "product": "hackney",
          "programFiles": [
            "src/hackney_ws.erl"
          ],
          "programRoutines": [
            {
              "name": "hackney_ws:read_handshake_response/3"
            },
            {
              "name": "hackney_ws:parse_payload/9"
            },
            {
              "name": "hackney_ws:parse_active_payload/8"
            }
          ],
          "repo": "https://github.com/benoitc/hackney",
          "vendor": "benoitc",
          "versions": [
            {
              "lessThan": "4.0.1",
              "status": "affected",
              "version": "2.0.0",
              "versionType": "semver"
            }
          ]
        },
        {
          "collectionURL": "https://github.com",
          "cpes": [
            "cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "hackney_ws"
          ],
          "packageName": "benoitc/hackney",
          "packageURL": "pkg:github/benoitc/hackney",
          "product": "hackney",
          "programFiles": [
            "src/hackney_ws.erl"
          ],
          "programRoutines": [
            {
              "name": "hackney_ws:read_handshake_response/3"
            },
            {
              "name": "hackney_ws:parse_payload/9"
            },
            {
              "name": "hackney_ws:parse_active_payload/8"
            }
          ],
          "repo": "https://github.com/benoitc/hackney",
          "vendor": "benoitc",
          "versions": [
            {
              "lessThan": "ce0109e2970ace6e20ff29bae9d05c3ac22ec6dc",
              "status": "affected",
              "version": "690cecaf236fba49526da404a5bc889a24367a3e",
              "versionType": "git"
            }
          ]
        }
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "B119C170-E9CA-4AEE-BE04-F074E70CBF82",
              "versionEndExcluding": "4.0.1",
              "versionStartIncluding": "2.0.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Allocation of Resources Without Limits or Throttling vulnerability in benoitc hackney allows Flooding. The WebSocket client in src/hackney_ws.erl imposes no upper bound on memory consumption in three code paths. First, read_handshake_response/3 accumulates received bytes into a growing buffer with no size cap; the per-receive timeout resets on every chunk, so a server that streams bytes without ever sending \\r\\n\\r\\n causes the buffer to grow until memory is exhausted. Second, parse_payload/9 and parse_active_payload/8 do not validate the declared frame payload length against any limit; because RFC 6455 allows payload lengths up to 2^63-1 bytes, a server that announces a very large frame and dribbles bytes causes the accumulation buffer to grow until OOM. Third, the frag_buffer field in #ws_data{} accumulates continuation frames indefinitely; a server that sends an endless stream of non-final (nofin) fragmented frames without ever sending a final (fin) frame grows frag_buffer without bound.\n\nIn all three cases the attacker only needs to control the WebSocket server the hackney client connects to, with no authentication or special client configuration required.\n\nThis issue affects hackney: from 2.0.0 before 4.0.1."
    }
  ],
  "id": "CVE-2026-47073",
  "lastModified": "2026-06-17T10:54:18.090",
  "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"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "cvssMetricV40": [
      {
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          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
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          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 8.7,
          "baseSeverity": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "HIGH",
          "vulnConfidentialityImpact": "NONE",
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    "ssvcV203": [
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        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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          "id": "CVE-2026-47073",
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            {
              "exploitation": "poc"
            },
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            },
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            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-05-26T15:44:41.043069Z",
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  "published": "2026-05-25T15:16:22.410",
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    },
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      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "tags": [
        "Patch"
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      "url": "https://github.com/benoitc/hackney/commit/ce0109e2970ace6e20ff29bae9d05c3ac22ec6dc"
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        "Patch",
        "Third Party Advisory"
      ],
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-47073"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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        "Exploit",
        "Patch",
        "Vendor Advisory"
      ],
      "url": "https://github.com/benoitc/hackney/security/advisories/GHSA-q8jg-fgj4-fphf"
    }
  ],
  "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
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        {
          "lang": "en",
          "value": "CWE-400"
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      "type": "Secondary"
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}

GHSA-Q8JG-FGJ4-FPHF

Vulnerability from github – Published: 2026-06-26 22:00 – Updated: 2026-06-26 22:00

Summary

Hackney has unbounded buffer accumulation in WebSocket

Details

Summary

The WebSocket client in src/hackney_ws.erl imposes no upper bound on memory consumption across three distinct code paths. In each case, an attacker-controlled WebSocket server can exhaust the connecting process's memory without any authentication or special client configuration.

Details

1. Handshake response buffer (read_handshake_response/3)

The function accumulates received bytes into a growing buffer waiting for \r\n\r\n. The per-receive timeout resets on every chunk, so a server that trickles bytes indefinitely without completing the HTTP upgrade response grows the buffer until OOM. No total-size cap exists.

2. Frame payload accumulation (parse_payload/9, parse_active_payload/8)

parse_payload/9 (lines 816–817 and 825–826) appends each received chunk into a Buffer binary via <<Buffer/binary, MoreData/binary>> whenever the frame parser returns {more, ...}. parse_active_payload/8 does the same in active mode by appending each incoming tcp/ssl message to #ws_data.buffer. RFC 6455 permits payload lengths up to 2⁶³-1 bytes, and neither path validates the declared Len against any limit. The recv_timeout applies per chunk, not to the whole frame, so a slow trickle never triggers it.

3. Fragmentation buffer (frag_buffer)

The frag_buffer field of #ws_data{} accumulates continuation frames. A server that sends an unbounded stream of non-final (nofin) fragments without ever sending a final (fin) frame grows frag_buffer without bound.

PoC

Stand up a WebSocket server and connect to it with hackney's WebSocket client.
Trigger any of the three paths: (a) never send \r\n\r\n during the handshake; (b) announce a very large frame payload and dribble bytes slowly; (c) send an endless stream of nofin continuation frames.
Observe the hackney process's memory growing until the BEAM OOM-kills it or the node crashes.

Impact

Denial of service via unbounded memory consumption. Affects hackney 2.0.0 through 4.0.0 for any application using the WebSocket client against an attacker-controlled server. No authentication or special configuration is required on the client side. CVSS v4.0: 8.7 (HIGH).

Resources

Introduction commit: https://github.com/benoitc/hackney/commit/690cecaf236fba49526da404a5bc889a24367a3e
Patch commit: https://github.com/benoitc/hackney/commit/ce0109e2970ace6e20ff29bae9d05c3ac22ec6dc

Severity

8.7 (High)


                  
                    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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Hex",
        "name": "hackney"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.0.0"
            },
            {
              "fixed": "4.0.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-47073"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-26T22:00:16Z",
    "nvd_published_at": "2026-05-25T15:16:22Z",
    "severity": "HIGH"
  },
  "details": "### Summary\n\nThe WebSocket client in `src/hackney_ws.erl` imposes no upper bound on memory consumption across three distinct code paths. In each case, an attacker-controlled WebSocket server can exhaust the connecting process\u0027s memory without any authentication or special client configuration.\n\n### Details\n\n**1. Handshake response buffer (`read_handshake_response/3`)**\n\nThe function accumulates received bytes into a growing buffer waiting for `\\r\\n\\r\\n`. The per-receive timeout resets on every chunk, so a server that trickles bytes indefinitely without completing the HTTP upgrade response grows the buffer until OOM. No total-size cap exists.\n\n**2. Frame payload accumulation (`parse_payload/9`, `parse_active_payload/8`)**\n\n`parse_payload/9` (lines 816\u2013817 and 825\u2013826) appends each received chunk into a `Buffer` binary via `\u003c\u003cBuffer/binary, MoreData/binary\u003e\u003e` whenever the frame parser returns `{more, ...}`. `parse_active_payload/8` does the same in active mode by appending each incoming `tcp`/`ssl` message to `#ws_data.buffer`. RFC 6455 permits payload lengths up to 2\u2076\u00b3-1 bytes, and neither path validates the declared `Len` against any limit. The `recv_timeout` applies per chunk, not to the whole frame, so a slow trickle never triggers it.\n\n**3. Fragmentation buffer (`frag_buffer`)**\n\nThe `frag_buffer` field of `#ws_data{}` accumulates continuation frames. A server that sends an unbounded stream of non-final (`nofin`) fragments without ever sending a final (`fin`) frame grows `frag_buffer` without bound.\n\n### PoC\n\n1. Stand up a WebSocket server and connect to it with hackney\u0027s WebSocket client.\n2. Trigger any of the three paths: (a) never send `\\r\\n\\r\\n` during the handshake; (b) announce a very large frame payload and dribble bytes slowly; (c) send an endless stream of `nofin` continuation frames.\n3. Observe the hackney process\u0027s memory growing until the BEAM OOM-kills it or the node crashes.\n\n### Impact\n\nDenial of service via unbounded memory consumption. Affects hackney 2.0.0 through 4.0.0 for any application using the WebSocket client against an attacker-controlled server. No authentication or special configuration is required on the client side. CVSS v4.0: **8.7 (HIGH)**.\n\n## Resources\n\n* Introduction commit: https://github.com/benoitc/hackney/commit/690cecaf236fba49526da404a5bc889a24367a3e\n* Patch commit: https://github.com/benoitc/hackney/commit/ce0109e2970ace6e20ff29bae9d05c3ac22ec6dc",
  "id": "GHSA-q8jg-fgj4-fphf",
  "modified": "2026-06-26T22:00:16Z",
  "published": "2026-06-26T22:00:16Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/benoitc/hackney/security/advisories/GHSA-q8jg-fgj4-fphf"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-47073"
    },
    {
      "type": "WEB",
      "url": "https://github.com/benoitc/hackney/commit/ce0109e2970ace6e20ff29bae9d05c3ac22ec6dc"
    },
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-47073.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/benoitc/hackney"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-47073"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Hackney has unbounded buffer accumulation in WebSocket"
}

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.

Action not permitted

CVE-2026-47073 (GCVE-0-2026-47073)

FKIE_CVE-2026-47073

GHSA-Q8JG-FGJ4-FPHF

Summary

Details

PoC

Impact

Resources

Tags

Sightings

Nomenclature