dbcve.org
SymfonyFramework / library · Sensiolabs

CVE-2026-45077

HIGH · 8.6 CVSS v3.1 Published 2026-07-14
Fix available
A fix is available. Upgrade to 5.4.52 / 6.4.40 or later.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click 5 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to 5.4.52, 6.4.40, 7.4.12, and 8.0.12, the server:log listener (Symfony\Bridge\Monolog\Command\ServerLogCommand) binds to 0.0.0.0:9911 by default and processes each received frame with unserialize(base64_decode($message)) without authentication, integrity checks, or an allowed_classes allowlist, allowing any reachable host to submit attacker-chosen serialized PHP payloads that can crash the listener and may trigger object-injection gadget effects. This issue is fixed in versions 5.4.52, 6.4.40, 7.4.12, and 8.0.12.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The ServerLogCommand in Symfony's Monolog bridge binds to 0.0.0.0:9911 by default and processes incoming frames using unsafe unserialize(base64_decode($message)) without authentication, integrity checks, or an allowed_classes allowlist, enabling remote unauthenticated attackers to inject malicious serialized PHP objects leading to potential code execution or denial of service.

MitigationUpdate Symfony to version 5.4.52, 6.4.40, 7.4.12, 8.0.12 or later. Alternatively, restrict network access to port 9911 or disable the server:log command in production environments.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
SymfonyFramework / library
Affected:< 5.4.52>= 6.0.0, < 6.4.40>= 7.0.0, < 7.4.12>= 8.0.0, < 8.0.12

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Symfony version
    Run 'bin/console --version' or check your composer.json require section for the symfony/*n version
    Affected if The reported version falls within any of these ranges: < 5.4.52, >= 6.0.0 and < 6.4.40, >= 7.0.0 and < 7.4.12, >= 8.0.0 and < 8.0.12
  2. Check if server:log command is in use
    Search your codebase or deployment scripts for 'server:log' command usage, or check running processes for 'bin/console server:log'
    Affected if The server:log command is actively running or configured to run as a service
  3. Verify if port 9911 is listening
    Run 'netstat -tlnp | grep 9911' or 'ss -tlnp | grep 9911' on the server to check if port 9911 is bound
    Affected if Port 9911 is listening on any interface, especially 0.0.0.0
  4. Confirm network exposure of the service
    Review firewall rules or network configuration to determine if port 9911 is accessible from untrusted networks
    Affected if Port 9911 is exposed to network segments that contain untrusted users or systems

You are affected if your Symfony version is within the vulnerable ranges AND the server:log command is running with port 9911 accessible on the network.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.4.52 / 6.4.40 / 7.4.12 or later
Fixed in 5.4.526.4.407.4.12
Interim mitigation

Update Symfony to version 5.4.52, 6.4.40, 7.4.12, 8.0.12 or later. Alternatively, restrict network access to port 9911 or disable the server:log command in production environments.

Recommended fix High confidence

5.4.52 (for 5.x) | 6.4.40 (for 6.x) | 7.4.12 (for 7.x) | 8.0.12 (for 8.x)

  1. Identify the currently installed Symfony version by running `composer show symfony/symfony` or checking your `composer.lock` file
  2. Determine which version branch you are on (5.x, 6.x, 7.x, or 8.x)
  3. Run `composer require symfony/symfony:"5.4.52" --no-interaction` if on the 5.x branch
  4. Run `composer require symfony/symfony:"6.4.40" --no-interaction` if on the 6.x branch
  5. Run `composer require symfony/symfony:"7.4.12" --no-interaction` if on the 7.x branch
  6. Run `composer require symfony/symfony:"8.0.12" --no-interaction` if on the 8.x branch
  7. Run `composer update symfony/symfony --with-all-dependencies` to update dependencies
  8. Verify the installed version with `composer show symfony/symfony`
Caveat Patch releases within the same minor version are typically low-risk, but review the Symfony CHANGELOG for any changes between your version and the target fixed version to ensure compatibility with your application code

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Symfony Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-45077 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-45077 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data