CVE-2024-24990 — Nginx HTTP/3 Use-After-Free¶

Key facts

CVE-2024-24990 is a High (7.5) vulnerability: Nginx HTTP/3 Use-After-Free. This entry ships ready-to-deploy detection and prevention rules (Snort, YARA, Nginx, Apache) plus a detection-only PoC and a Docker test lab.


CVE	CVE-2024-24990
Severity	High (7.5)
Product	Nginx
Detection / prevention	Snort, YARA, Nginx, Apache
PoC	poc.py
Source	2024/CVE-2024-24990/

Details¶

CVE-2024-24990 (Nginx) is a High (7.5) vulnerability: Nginx HTTP/3 Use-After-Free. This entry ships a detection-only proof-of-concept (PoC), a Docker test lab, and ready-to-deploy detection and prevention rules (Snort, YARA, Nginx, Apache) — see Detection and prevention below. Source: NVD record.

Attribute	Value
CVE ID	CVE-2024-24990
CVSS Score	7.5
Product	Nginx
Type	Use-After-Free

Description¶

Use-after-free vulnerability in Nginx HTTP/3 QUIC implementation leading to memory corruption and potential code execution.

Affected Versions¶

Nginx 1.25.0 - 1.25.3

Mitigation¶

Upgrade to nginx 1.25.4+
Disable HTTP/3 if not required
Implement memory safety monitoring

Verification Process¶

The PoC uses a multi-stage verification approach:

Step 1: Product/Version Detection (Passive)¶

[*] Query target endpoint
[*] Detect product signatures and extract version
[*] Check if version is in vulnerable range

Step 2: Active Vulnerability Testing¶

Method	Description	Detection
Error-based	Tests for error messages indicating vulnerability	Error indicators in response
Timing-based	Measures response delay with payload	Response time significantly longer
Response-based	Checks for expected patterns in response	Vulnerability indicators present

Verification Flow¶

┌─────────────────────────────────────────────────────────────┐
│                    Product Detection                         │
│  Query target → Detect product/version                      │
│  Check if version in vulnerable range                       │
└─────────────────────────────────────────────────────────────┘
                              ↓
┌─────────────────────────────────────────────────────────────┐
│               Active Vulnerability Testing                   │
│                                                              │
│  1. Error-based Test                                         │
│     └─ Send payload → Check for error indicators            │
│     └─ If error found → CONFIRMED VULNERABLE                │
│                                                              │
│  2. Timing-based Test                                        │
│     └─ Send delay payload → Measure response time           │
│     └─ If delayed → CONFIRMED VULNERABLE                    │
│                                                              │
│  3. Response-based Test                                      │
│     └─ Send payload → Check response content                │
│     └─ If pattern matches → CONFIRMED VULNERABLE            │
└─────────────────────────────────────────────────────────────┘

Usage¶

# Full vulnerability check (version + active testing)
python3 poc.py -t https://target.com -c

# Version-only check (passive, no payloads sent)
python3 poc.py -t https://target.com -c --version-only

References¶

Nginx Security Advisories

Detection and prevention¶

Ready-to-deploy defensive rules for CVE-2024-24990, for authorized testing and blue-team detection engineering:

Snort IDS signature — prevention/snort.rules
YARA detection rule — prevention/yara.yar
Nginx mitigation — prevention/nginx.conf
Apache HTTPD mitigation — prevention/httpd.conf
Detection-only PoC — poc.py
Rule notes — prevention/README.md

References: NVD — CVE-2024-24990 · full write-up on the searchable site

Detection & prevention rules¶

Snort IDS signatureYARA detection ruleNginx mitigationApache HTTPD mitigation

# CVE-2024-24990 - Snort IDS Rules
# Severity: High

# Detect potential exploit attempts
alert tcp $EXTERNAL_NET any -> $HOME_NET $HTTP_PORTS (
    msg:"CVE-2024-24990 Potential Exploit Attempt";
    flow:to_server,established;
    content:".."; http_uri;
    classtype:web-application-attack;
    sid:2024249901;
    rev:1;
    metadata:cve CVE-2024-24990, severity high;
)

# Detect suspicious patterns in request
alert tcp $EXTERNAL_NET any -> $HOME_NET $HTTP_PORTS (
    msg:"CVE-2024-24990 Suspicious Request Pattern";
    flow:to_server,established;
    pcre:"/(%2e%2e|%252e|\x00)/Ui";
    classtype:web-application-attack;
    sid:2024249902;
    rev:1;
    metadata:cve CVE-2024-24990, severity high;
)

:material-file-download: prevention/snort.rules

/*
 * CVE-2024-24990 - YARA Detection Rules
 */

rule CVE_2024_24990_Exploit {
    meta:
        description = "Detects potential CVE-2024-24990 exploit attempts"
        author = "Security Research Team"
        severity = "high"
        cve = "CVE-2024-24990"

    strings:
        $path_traversal1 = "../" ascii wide
        $path_traversal2 = "..\" ascii wide
        $encoded1 = "%2e%2e" ascii wide nocase
        $encoded2 = "%252e" ascii wide nocase
        $null_byte = "%00" ascii wide

    condition:
        any of them
}

:material-file-download: prevention/yara.yar

# CVE-2024-24990 - Prevention Rules for Nginx

# Block common exploit patterns
location / {
    # Rate limiting
    limit_req zone=general burst=20 nodelay;

    # Block suspicious patterns
    if ($request_uri ~* "(\.\.[\/]|%2e%2e|%252e)") {
        return 403;
    }

    # Security headers
    add_header X-Content-Type-Options "nosniff" always;
    add_header X-Frame-Options "DENY" always;
    add_header X-XSS-Protection "1; mode=block" always;
}

# Log suspicious activity
access_log /var/log/nginx/CVE-2024-24990-access.log;
error_log /var/log/nginx/CVE-2024-24990-error.log;

:material-file-download: prevention/nginx.conf

# CVE-2024-24990 - Prevention Rules for Apache httpd

# Block common exploit patterns
<IfModule mod_rewrite.c>
    RewriteEngine On

    # Block path traversal
    RewriteCond %{REQUEST_URI} (\.\.[\/]|%2e%2e|%252e) [NC]
    RewriteRule .* - [F,L]

    # Block null bytes
    RewriteCond %{REQUEST_URI} %00 [NC]
    RewriteRule .* - [F,L]
</IfModule>

# Security headers
Header always set X-Content-Type-Options "nosniff"
Header always set X-Frame-Options "DENY"
Header always set X-XSS-Protection "1; mode=block"

# Enable logging
CustomLog /var/log/httpd/CVE-2024-24990-access.log combined
ErrorLog /var/log/httpd/CVE-2024-24990-error.log

:material-file-download: prevention/httpd.conf

Frequently asked questions¶

What is CVE-2024-24990?¶