Vulnerability-Lookup

GHSA-GP9C-PM5M-5CXR

Vulnerability from github – Published: 2026-06-26 21:53 – Updated: 2026-06-26 21:53

Summary

Hackney: `ssl:connect/2` post-handshake upgrade has no timeout

Details

Summary

The SOCKS5 transport in src/hackney_socks5.erl correctly applies the caller-supplied timeout to the SOCKS5 negotiation phase, but then upgrades the tunnel to TLS using ssl:connect/2 (the two-argument form), which defaults to infinity. The Timeout value is in scope at that call site but is never forwarded. A hostile or man-in-the-middled SOCKS5 proxy that completes the SOCKS5 handshake normally and then stalls the TLS exchange will pin the connecting Erlang process and socket indefinitely, regardless of any connect_timeout or recv_timeout options the caller set.

Details

In src/hackney_socks5.erl, line 65, after the SOCKS5 negotiation succeeds, the code calls:

ssl:connect(Socket, SSLOpts)

The three-argument form ssl:connect/3 takes a timeout; the two-argument form used here defaults to infinity. The variable Timeout (already used for SOCKS5 recv calls earlier in the same function) is simply not passed. The bytes that drive the TLS handshake on the upstream side of the tunnel come from whatever endpoint the proxy connects to. A hostile proxy can complete SOCKS5 normally, then either stay silent or send a partial ServerHello and stop, keeping ssl:connect/2 blocked forever. No certificate forgery is needed.

PoC

Stand up a SOCKS5 proxy that completes the SOCKS5 greeting and CONNECT reply normally, then goes silent (never sends a TLS ServerHello).
Issue an HTTPS request through it via hackney with connect_timeout and recv_timeout set to a short value (e.g. 2000 ms).
Observe the calling process remains blocked well past the configured timeout, consuming a process and socket until killed externally.

Impact

Denial of service via unbounded process and socket consumption. Affects hackney 0.10.0 through 4.0.0 for any HTTPS request routed through a SOCKS5 proxy. The connect_timeout and recv_timeout options give a false sense of safety since they are not honored during the TLS upgrade. CVSS v4.0: 8.2 (HIGH).

Resources

Introduction commit: https://github.com/benoitc/hackney/commit/34cdbd1d20a282aacc286a89327465a3925b4c5d
Patch commit: https://github.com/benoitc/hackney/commit/5ccdab725c561a6f03d05a51f2d0664f98236dae

Severity

8.2 (High)


                  
                    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

Show details on source website

JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Hex",
        "name": "hackney"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.10.0"
            },
            {
              "fixed": "4.0.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-47071"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-26T21:53:50Z",
    "nvd_published_at": "2026-05-25T15:16:22Z",
    "severity": "HIGH"
  },
  "details": "### Summary\n\nThe SOCKS5 transport in `src/hackney_socks5.erl` correctly applies the caller-supplied timeout to the SOCKS5 negotiation phase, but then upgrades the tunnel to TLS using `ssl:connect/2` (the two-argument form), which defaults to `infinity`. The `Timeout` value is in scope at that call site but is never forwarded. A hostile or man-in-the-middled SOCKS5 proxy that completes the SOCKS5 handshake normally and then stalls the TLS exchange will pin the connecting Erlang process and socket indefinitely, regardless of any `connect_timeout` or `recv_timeout` options the caller set.\n\n### Details\n\nIn `src/hackney_socks5.erl`, line 65, after the SOCKS5 negotiation succeeds, the code calls:\n\n```erlang\nssl:connect(Socket, SSLOpts)\n```\n\nThe three-argument form `ssl:connect/3` takes a timeout; the two-argument form used here defaults to `infinity`. The variable `Timeout` (already used for SOCKS5 recv calls earlier in the same function) is simply not passed. The bytes that drive the TLS handshake on the upstream side of the tunnel come from whatever endpoint the proxy connects to. A hostile proxy can complete SOCKS5 normally, then either stay silent or send a partial `ServerHello` and stop, keeping `ssl:connect/2` blocked forever. No certificate forgery is needed.\n\n### PoC\n\n1. Stand up a SOCKS5 proxy that completes the SOCKS5 greeting and CONNECT reply normally, then goes silent (never sends a TLS ServerHello).\n2. Issue an HTTPS request through it via hackney with `connect_timeout` and `recv_timeout` set to a short value (e.g. 2000 ms).\n3. Observe the calling process remains blocked well past the configured timeout, consuming a process and socket until killed externally.\n\n### Impact\n\nDenial of service via unbounded process and socket consumption. Affects hackney 0.10.0 through 4.0.0 for any HTTPS request routed through a SOCKS5 proxy. The `connect_timeout` and `recv_timeout` options give a false sense of safety since they are not honored during the TLS upgrade. CVSS v4.0: **8.2 (HIGH)**.\n\n## Resources\n\n* Introduction commit: https://github.com/benoitc/hackney/commit/34cdbd1d20a282aacc286a89327465a3925b4c5d\n* Patch commit: https://github.com/benoitc/hackney/commit/5ccdab725c561a6f03d05a51f2d0664f98236dae",
  "id": "GHSA-gp9c-pm5m-5cxr",
  "modified": "2026-06-26T21:53:50Z",
  "published": "2026-06-26T21:53:50Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/benoitc/hackney/security/advisories/GHSA-gp9c-pm5m-5cxr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-47071"
    },
    {
      "type": "WEB",
      "url": "https://github.com/benoitc/hackney/commit/5ccdab725c561a6f03d05a51f2d0664f98236dae"
    },
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-47071.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/benoitc/hackney"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-47071"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Hackney: `ssl:connect/2` post-handshake upgrade has no timeout"
}

CVE-2026-47071 (GCVE-0-2026-47071)

Vulnerability from cvelistv5 – Published: 2026-05-25 14:00 – Updated: 2026-05-27 15:40

Title

SOCKS5 TLS upgrade ignores caller timeout in hackney

Summary

Uncontrolled Resource Consumption vulnerability in benoitc hackney allows Flooding. The SOCKS5 transport in src/hackney_socks5.erl correctly applies the caller-supplied timeout to the SOCKS5 negotiation phase, but then upgrades the connection to TLS using the two-argument form ssl:connect/2, which defaults to an infinite timeout. The Timeout value is in scope at the call site but is not forwarded. A hostile SOCKS5 proxy that completes the SOCKS5 handshake normally and then goes silent (or sends a partial TLS ServerHello and stalls) will cause the connecting process to block indefinitely, regardless of the connect_timeout or recv_timeout options supplied by the caller. This issue affects hackney: from 0.10.0 before 4.0.1.

Severity

8.2 (High)


                        
                          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

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-2026-47071.html	related
https://osv.dev/vulnerability/EEF-CVE-2026-47071	related
https://github.com/benoitc/hackney/commit/5ccdab7…	patch

Impacted products

2 products

Vendor	Product	Version
benoitc	hackney	Affected: 0.10.0 , < 4.0.1 (semver) cpe:2.3:a:benoitc:hackney::::::::
benoitc	hackney	Affected: 34cdbd1d20a282aacc286a89327465a3925b4c5d , < 5ccdab725c561a6f03d05a51f2d0664f98236dae (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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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.

Action not permitted

GHSA-GP9C-PM5M-5CXR

Summary

Details

PoC

Impact

Resources

CVE-2026-47071 (GCVE-0-2026-47071)

Tags

Sightings

Nomenclature