What’s Vulnerable › Vulnerabilities

CVE-2026-47071: SOCKS5 TLS upgrade ignores caller timeout in hackney

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-05-25 · updated 2026-07-24
• Weakness: CWE-400

Description

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.

Affected products

• benoitc hackney: from 0.10.0 before 4.0.1 — fixed in 4.0.1

How to fix

Upgrade to a fixed version: benoitc hackney 4.0.1. Check the vendor advisory for mitigations.

References

• https://cna.erlef.org/cves/CVE-2026-47071.html
• https://github.com/benoitc/hackney/commit/5ccdab725c561a6f03d05a51f2d0664f98236dae
• https://github.com/benoitc/hackney/security/advisories/GHSA-gp9c-pm5m-5cxr
• https://osv.dev/vulnerability/EEF-CVE-2026-47071
• https://github.com/benoitc/hackney/security/advisories/GHSA-gp9c-pm5m-5cxr

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