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Zend FrameworkApplication · Zend

CVE-2015-1555

CRITICAL · 9.1 CVSS v3.0 Published 2017-08-07
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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
Zend/Session/SessionManager in Zend Framework 2.2.x before 2.2.9, 2.3.x before 2.3.4 allows remote attackers to create valid sessions without using session validators.

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

Zend Framework's SessionManager component in versions 2.2.x before 2.2.9 and 2.3.x before 2.3.4 contains a session validation bypass vulnerability. The flaw allows remote attackers to create valid sessions without utilizing the framework's session validators, potentially enabling session hijacking or fixation attacks.

MitigationUpgrade Zend Framework to version 2.2.9 or later, or 2.3.4 or later to incorporate the patched SessionManager with proper session validation enforcement.

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
Zend FrameworkApplication
Affected:= 2.2.0= 2.2.1= 2.2.2= 2.2.3= 2.2.4= 2.2.5= 2.2.6= 2.2.7= 2.2.8= 2.3.0= 2.3.1= 2.3.2

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
High
Integrity
High
Availability
None

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

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 Zend Framework version
    Locate the Zend Framework library in your application (typically in vendor/zendframework or a similar vendor directory) and check the version.php or composer.json file to determine the installed version number
    Affected if The installed version is 2.2.0 through 2.2.8, or 2.3.0 through 2.3.2
  2. Verify SessionManager is in use
    Search your application codebase for usage of Zend\Session\SessionManager or Zend\Session\Container classes, which indicate the vulnerable component is active
    Affected if Your application uses SessionManager or Session containers from Zend Framework and the version falls within the affected range
  3. Inspect session configuration
    Check your application's session configuration (typically in config/autoload or module config files) for how session validators are defined. Look for any session config files that specify validator chain settings
    Affected if SessionManager is being used but validators may not be properly enforced due to the bypass vulnerability in affected versions
  4. Check session initialization code
    Review code that initializes sessions, particularly any calls to SessionManager::start() or session_start(), to see if validator chain validation occurs before session data is accessible
    Affected if Sessions are started without proper validator chain validation, which is the behavior enabled by this vulnerability in affected versions

You are affected if your application runs any version of Zend Framework 2.2.0-2.2.8 or 2.3.0-2.3.2 and uses the SessionManager component without additional validation safeguards.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Zend Framework to version 2.2.9 or later, or 2.3.4 or later to incorporate the patched SessionManager with proper session validation enforcement.

Recommended fix High confidence

2.2.9 (for 2.2.x branches) or 2.3.4/2.4.x (for newer branches)

  1. Check the current Zend Framework version in your composer.json file
  2. Run 'composer update zendframework/zendframework --with-all-dependencies' to update to the latest 2.2.x release (2.2.9) or upgrade to a newer stable branch
  3. Alternatively, run 'composer require zendframework/zendframework:2.3.4' or 'composer require zendframework/zendframework:^2.4' to specify the target version
  4. After upgrading, verify that your SessionManager configuration includes session validators (e.g., Zend\Session\Validator\RemoteAddr, Zend\Session\Validator\HttpUserAgent)
  5. Test that session validation is functioning correctly in your application
Caveat Upgrading between major version branches (e.g., 2.2 to 2.4 or 3.x) may introduce breaking changes due to API modifications; review the migration guide for your target version

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

Fix this in Zend Framework Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,380
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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-2015-1555 in production — separate from our analysis above.

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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