CVE-2026-1788

N/A Unknown
Denial of Service Buffer Overflow

📋 TL;DR

CVE-2026-1788 is an out-of-bounds write vulnerability in Xquic Server's packet processing module that allows attackers to manipulate buffers. This affects Xquic Server versions through 1.8.3 on Linux systems. Organizations using Xquic Server for QUIC protocol implementation are vulnerable to potential exploitation.

💻 Affected Systems

Products:
  • Xquic Server
Versions: through 1.8.3
Operating Systems: Linux
Default Config Vulnerable: ⚠️ Yes
Notes: Affects the QUIC packet processing module; any Xquic Server deployment using vulnerable versions is affected

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution leading to complete system compromise, data exfiltration, or service disruption

🟠

Likely Case

Denial of service through server crashes or instability in QUIC packet processing

🟢

If Mitigated

Limited impact if proper network segmentation and least privilege principles are implemented

🌐 Internet-Facing: HIGH - QUIC servers are typically internet-facing and process untrusted network packets
🏢 Internal Only: MEDIUM - Internal QUIC services could still be targeted through lateral movement

🎯 Exploit Status

Public PoC: ✅ No
Weaponized: UNKNOWN
Unauthenticated Exploit: ⚠️ Yes
Complexity: MEDIUM

Out-of-bounds write vulnerabilities in network processing code are often exploitable but require specific packet crafting

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Not yet released

Vendor Advisory: https://github.com/alibaba/xquic

Restart Required: Yes

Instructions:

1. Monitor the Xquic GitHub repository for security updates
2. When patch is released, download the latest version
3. Replace vulnerable Xquic Server installation with patched version
4. Restart Xquic Server services

🔧 Temporary Workarounds

Network segmentation and filtering

linux

Restrict access to Xquic Server ports using firewall rules

iptables -A INPUT -p udp --dport 443 -j DROP
iptables -A INPUT -p udp --dport 443 -s trusted_network -j ACCEPT

🧯 If You Can't Patch

  • Implement strict network access controls to limit exposure to trusted sources only
  • Deploy intrusion detection systems to monitor for anomalous QUIC packet patterns

🔍 How to Verify

Check if Vulnerable:

Check Xquic Server version: xquic --version or examine installed package version

Check Version:

xquic --version || dpkg -l | grep xquic || rpm -qa | grep xquic

Verify Fix Applied:

After patching, verify version is above 1.8.3 and test QUIC connectivity

📡 Detection & Monitoring

Log Indicators:

  • Xquic Server crash logs
  • Memory access violation errors in system logs
  • Abnormal QUIC connection terminations

Network Indicators:

  • Malformed QUIC packets with unusual payloads
  • High volume of QUIC connection attempts from single sources

SIEM Query:

source="xquic.log" AND (error OR crash OR segmentation)

📊 Metadata

CVE ID: CVE-2026-1788
CVSS v3 Score: N/A (Unknown)
CWE: CWE-787
Published: February 3, 2026
Last Updated: February 4, 2026

🤖 AI-assisted analysis, reviewed for accuracy

🔗 References

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