Is CVE-2026-118515 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-118515 being exploited in the wild.

How severe is CVE-2026-118515?

Informational severity, published 6 November 2026.

Which products and versions are affected?

Symfony Serializer component prior to 5.4.56, 6.x prior to 6.4.50, 7.x prior to 7.4.23, 8.x prior to 8.1.11.

How is CVE-2026-118515 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-118515?

Check whether you run Symfony Serializer component at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-118515: Symfony Serializer arbitrary file handling via DataUriNormalizer

CVE-2026-118515 · Severity: info · Published 2026-11-06

Symfony's Serializer component can be tricked into treating arbitrary files on a server as uploaded files when deserializing untrusted data. An attacker can craft a malicious request to access, expose, or move any file readable by the PHP process without sending it as a genuine upload, potentially exposing sensitive configuration files like .env.local or facilitating file manipulation attacks.

Vendors: Symfony.

Quick answers

Is CVE-2026-118515 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-118515 being exploited in the wild.
How severe is CVE-2026-118515?: Informational severity, published 6 November 2026.
Which products and versions are affected?: Symfony Serializer component prior to 5.4.56, 6.x prior to 6.4.50, 7.x prior to 7.4.23, 8.x prior to 8.1.11.
Is there a fix for CVE-2026-118515?: Yes: fixed in Symfony 5.4.56, 6.4.50, 7.4.23, 8.1.11. Until then: Ensure DataUriNormalizer is configured ahead of ObjectNormalizer in the serializer; the default FrameworkBundle configuration is protected by this fix. Avoid deserializing untrusted data into types with UploadedFile properties, particularly when using #[MapRequestPayload] on DTOs without authentication checks. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-118515 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-118515?: Check whether you run Symfony Serializer component at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: Symfony 5.4.56, 6.4.50, 7.4.23, 8.1.11

Ensure DataUriNormalizer is configured ahead of ObjectNormalizer in the serializer; the default FrameworkBundle configuration is protected by this fix. Avoid deserializing untrusted data into types with UploadedFile properties, particularly when using #[MapRequestPayload] on DTOs without authentication checks.

Technical details

The DataUriNormalizer only recognizes exact types SplFileInfo, SplFileObject, and File, so subclasses like UploadedFile bypass the normalizer and are instantiated through ObjectNormalizer with attacker-controlled constructor arguments including arbitrary file paths. By setting test: true in the request payload, UploadedFile::isValid() skips the is_uploaded_file() check, and move() falls back to rename(), allowing arbitrary file operations. File validation assertions do not prevent this since they validate against the attacker-chosen path on the server.

Affected products

Symfony Serializer component prior to 5.4.56, 6.x prior to 6.4.50, 7.x prior to 7.4.23, 8.x prior to 8.1.11

Timeline

2026-11-06: disclosed

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