EEF-CVE-2026-47071 CVE-2026-47071 GHSA-gp9c-pm5m-5cxr
SOCKS5 TLS upgrade ignores caller timeout in hackney
- Severity
- 0.0 / 10
- High · CVSS 4.0
- Exploit chance (EPSS)
- 0.75%
- Chance of exploitation in the next 30 days. Higher than 55.08% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-400 Uncontrolled Resource Consumption
- Fix
4.0.1- Upgrade hackney to this version or later
Description
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.
Affected versions
Hex
| Package | Vulnerable | Fixed in |
|---|---|---|
| hackney | >= 0.10.0, < 4.0.1 |
4.0.1 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
hackney Hex → 4.0.1
- mix
{:hackney, "~> 4.0.1"} # then: mix deps.update hackney
Severity breakdown
CVSS 4.0 0.0
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
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- Present
- Privileges required
- None
- User interaction
- None
- Confidentiality (vulnerable system)
- None
- Integrity (vulnerable system)
- None
- Availability (vulnerable system)
- High
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
CVSS 3.1 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Weakness
CWE-400: Uncontrolled Resource Consumption
The product does not properly control the allocation and maintenance of a limited resource.
How to prevent it
- Architecture and Design: Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place. The login application should be protected against DoS attacks as much as possible. Limiting the database access, perhaps by caching result sets, can help minimize the resources expended. To further limit the potential for a DoS attack, consider tracking the rate of requests received from users and blocking requests that exceed a defined rate threshold.
- Architecture and Design: Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed. The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question. The second solution is simply difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.
- Architecture and Design: Ensure that protocols have specific limits of scale placed on them.
- Implementation: Ensure that all failures in resource allocation place the system into a safe posture.
References
Advisories
Fixes and patches
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| EEF-CVE-2026-97200 Unbounded response body buffering and decompression in hackney | Not rated yet | Also affects hackney |
| EEF-CVE-2026-115693 Custom cacerts or cacertfile do not restrict trust to the pinned CA in hackney | Not rated yet | Also affects hackney |
| EEF-CVE-2026-113440 HTTP/1.1 and HTTP/2 redirects resend basic_auth and cookie to a different scheme or port in hackney | Not rated yet | Also affects hackney |
| EEF-CVE-2026-115700 SSRF allowlist bypass via percent-encoded bracketed IPv6 or trailing-dot IP literal in hackney | Not rated yet | Also affects hackney |
| EEF-CVE-2026-112880 CRLF injection in Proxy-Authorization header built from proxy_auth_fun in hackney | Not rated yet | Also affects hackney |
| EEF-CVE-2026-47073 Unbounded memory consumption in WebSocket client in hackney | High | Also affects hackney |
| EEF-CVE-2026-47067 Atom table exhaustion via unrecognized URL schemes in hackney | High | Also affects hackney |
| EEF-CVE-2026-47072 CRLF injection in WebSocket upgrade request in hackney | High | Also affects hackney |
Credits: Benoit Chesneau, Jonatan Männchen / EEF, Peter Ullrich
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