GHSA-64hg-93w9-fc35 CVE-2026-45754
Symfony's Mailjet Mailer Webhook Parser Never Verifies the Configured Secret — Unauthenticated Webhook Event Injection
- Severity
- 0.0 / 10
- Medium · CVSS 4.0
- Exploit chance (EPSS)
- 0.45%
- Chance of exploitation in the next 30 days. Higher than 38.71% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Fix
- Available
- 3 packages have a fixed version
Description
Description
The Mailjet mailer bridge and the LOX24 SMS notifier bridge both ship webhook request parsers used to authenticate and decode the event callbacks each provider POSTs to an application's webhook endpoint. Their doParse(Request $request, #[\SensitiveParameter] string $secret) methods receive the configured webhook secret but never read it; they convert and return the payload unconditionally.
As a result, an application that wires up either webhook endpoint accepts any POST to that URL, even when a webhook secret is configured (the recommended setup). An attacker who knows the endpoint exists can submit forged event payloads, fake bounce / blocked / spam / open / click / delivery events, leading to suppression-list corruption, delivery-metrics fraud, etc.
Resolution
MailjetRequestParser::doParse() now rejects the request unless it carries the expected HTTP Basic credentials, Mailjet's webhook authentication mechanism, using a constant-time comparison. The configured webhook secret is matched against the credentials embedded in the Mailjet webhook URL as user:password (use :password when the URL has no username).
Lox24RequestParser::doParse() now rejects the request unless it carries an X-LOX24-Token HTTP header whose value matches the configured secret, using a constant-time comparison. The same token must be configured in the LOX24 dashboard under the callback settings.
When no secret is configured the behaviour is unchanged: webhook authentication remains opt-in, but it is now actually enforced once opted in.
The Mailjet patch is available here for branch 6.4.
The LOX24 patch is available here for branch 7.4 (the LOX24 bridge was introduced in 7.1 and is not present in 6.4).
Credits
Symfony would like to thank Himanshu Anand for reporting the issue, and Alexandre Daubois and Nicolas Grekas for providing the fixes.
Affected versions
Packagist
| Package | Vulnerable | Fixed in |
|---|---|---|
| symfony/lox24-notifier | >= 7.1.0, < 7.4.12 |
7.4.12 |
| symfony/lox24-notifier | >= 8.0.0, < 8.0.12 |
8.0.12 |
| symfony/mailjet-mailer | >= 6.4.0, < 6.4.40 |
6.4.40 |
| symfony/mailjet-mailer | >= 7.0.0, < 7.4.12 |
7.4.12 |
| symfony/mailjet-mailer | >= 8.0.0, < 8.0.12 |
8.0.12 |
| symfony/symfony | >= 6.4.0, < 6.4.40 |
6.4.40 |
| symfony/symfony | >= 7.0.0, < 7.4.12 |
7.4.12 |
| symfony/symfony | >= 8.0.0, < 8.0.12 |
8.0.12 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
symfony/lox24-notifier Packagist → 7.4.12
- composer
composer require symfony/lox24-notifier:^7.4.12
symfony/mailjet-mailer Packagist → 6.4.40
- composer
composer require symfony/mailjet-mailer:^6.4.40
symfony/symfony Packagist → 6.4.40
- composer
composer require symfony/symfony:^6.4.40
Severity breakdown
CVSS 4.0 0.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- None
- Privileges required
- None
- User interaction
- None
- Confidentiality (vulnerable system)
- None
- Integrity (vulnerable system)
- High
- Availability (vulnerable system)
- None
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
- Exploit maturity
- Unreported
CVSS 3.1 5.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
Weakness
CWE-287: Improper Authentication
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
How to prevent it
- Architecture and Design: Use an authentication framework or library such as the OWASP ESAPI Authentication feature.
CWE-306: Missing Authentication for Critical Function
The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.
How to prevent it
- Architecture and Design: Divide the software into anonymous, normal, privileged, and administrative areas. Identify which of these areas require a proven user identity, and use a centralized authentication capability. Identify all potential communication channels, or other means of interaction with the software, to ensure that all channels are appropriately protected, including those channels that are assumed to be accessible only by authorized parties. Developers sometimes perform authentication at the primary channel, but open up a secondary channel that is assumed to be private. For example, a login mechanism may be listening on one network port, but after successful authentication, it may open up a second port where it waits for the connection, but avoids authentication because it assumes that only the authenticated party will connect to the port. In general, if the software or protocol allows a single session or user state to persist across multiple connections or channels, authentication and appropriate credential management need to be used throughout.
- Architecture and Design: For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
- Architecture and Design: Where possible, avoid implementing custom, "grow-your-own" authentication routines and consider using authentication capabilities as provided by the surrounding framework, operating system, or environment. These capabilities may avoid common weaknesses that are unique to authentication; support automatic auditing and tracking; and make it easier to provide a clear separation between authentication tasks and authorization tasks. In environments such as the World Wide Web, the line between authentication and authorization is sometimes blurred. If custom authentication routines are required instead of those provided by the server, then these routines must be applied to every single page, since these pages could be requested directly.
- Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator [REF-45].
- Implementation, System Configuration, Operation: When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to require strong authentication for users who should be allowed to access the data [REF-1297] [REF-1298] [REF-1302].
References
Fixes and patches
Packages
Other links
- github.com/symfony/symfony/security/advisories/GHSA-64hg-93w9-fc35
- github.com/symfony/symfony/commit/4aaa45dd054f73445f1ab254968b7e60b546cc77
- github.com/FriendsOfPHP/security-advisories/blob/master/symfony/lox24-notifier/…
- github.com/FriendsOfPHP/security-advisories/blob/master/symfony/mailjet-mailer/…
- github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-202…
- symfony.com/cve-2026-45754
- github.com/symfony/symfony/releases/tag/v6.4.40
- github.com/symfony/symfony/releases/tag/v7.4.12
- github.com/symfony/symfony/releases/tag/v8.0.12
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-2v3c-qxhr-7vpv Symfony: Unbounded Recursion in the YAML Inline Lexer Lets a Single Document Crash the Process | High | Also affects symfony/symfony |
| GHSA-r925-mgvr-h9cc Symfony: ReDoS in HeaderUtils::split() Reachable Through the Cache-Control Request Header | High | Also affects symfony/symfony |
| GHSA-h5x3-xfc9-m39h Symfony: UrlGenerator Dot-Segment Encoding Skips Every Other Chained `../` or `./` → Generated URL Collapses Off-Route Under RFC 3986 Normalization | Medium | Also affects symfony/symfony |
| GHSA-v3wm-qf9p-c549 Symfony: HtmlSanitizer URL Parser Deny Gates Underinclusive: Percent-Encoded BiDi Marks and Unicode Whitespace Bypass Visual-Spoofing Defense | Medium | Also affects symfony/symfony |
| GHSA-rrj9-5q2j-4gvr Symfony: Mailomat Mailer Webhook Parser Reads the HMAC Algorithm from the Request: Signature Algorithm Downgrade | Medium | Also affects symfony/symfony |
| GHSA-38cx-cq6f-5755 Symfony: IpUtils::PRIVATE_SUBNETS Omits IPv6 Transition Forms (6to4, NAT64, Teredo, IPv4-compatible): SSRF Bypass in NoPrivateNetworkHttpClient | High | Also affects symfony/symfony |
| GHSA-6h46-9jf5-q59x Symfony: Security Firewall Bypass via failure_forward Subrequest: Unauthenticated Access to access_control-Protected GET Routes | High | Also affects symfony/symfony |
| GHSA-x5qj-865h-mgvm Symfony: HtmlSanitizer UrlAttributeSanitizer Misses URL Attributes | Medium | Also affects symfony/symfony |
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