CVE-2015-4050

CVE-2015-4050 is a medium-severity vulnerability in Sensiolabs Symfony with a CVSS 2.0 base score of 4.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-284.

Key facts

• Severity: Medium (CVSS 2.0 base score 4.3)
• EPSS exploit prediction: 8% (94th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-284
• Affected product: Sensiolabs Symfony
• Published: 2015-06-02
• Last modified: 2026-06-17

Description

FragmentListener in the HttpKernel component in Symfony 2.3.19 through 2.3.28, 2.4.9 through 2.4.10, 2.5.4 through 2.5.11, and 2.6.0 through 2.6.7, when ESI or SSI support enabled, does not check if the _controller attribute is set, which allows remote attackers to bypass URL signing and security rules by including (1) no hash or (2) an invalid hash in a request to /_fragment.

Frequently asked questions

What is CVE-2015-4050?

FragmentListener in the HttpKernel component in Symfony 2.3.19 through 2.3.28, 2.4.9 through 2.4.10, 2.5.4 through 2.5.11, and 2.6.0 through 2.6.7, when ESI or SSI support enabled, does not check if the _controller attribute is set, which allows remote attackers to bypass URL signing and security rules by including (1) no hash or (2) an invalid hash in a request to /_fragment.

How severe is CVE-2015-4050?

CVE-2015-4050 has a CVSS 2.0 base score of 4.3, rated medium severity.

Is CVE-2015-4050 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 8% (94th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2015-4050?

CVE-2015-4050 primarily affects Sensiolabs Symfony. In total, 27 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2015-4050?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2015-4050 published?

CVE-2015-4050 was published on 2015-06-02 and last updated on 2026-06-17.

References

• http://lists.fedoraproject.org/pipermail/package-announce/2015-June/159513.html
• http://lists.fedoraproject.org/pipermail/package-announce/2015-June/159603.html
• http://lists.fedoraproject.org/pipermail/package-announce/2015-June/159610.html
• http://symfony.com/blog/cve-2015-4050-esi-unauthorized-access
• http://www.debian.org/security/2015/dsa-3276
• http://www.securityfocus.com/bid/74928

Affected products (27)

• cpe:2.3:a:sensiolabs:symfony:2.3.19:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.3.20:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.3.21:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.3.22:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.3.23:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.3.24:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.3.25:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.3.26:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.3.27:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.3.28:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.4.9:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.4.10:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.5.4:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.5.5:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.5.6:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.5.7:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.5.8:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.5.9:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.5.10:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.5.11:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.6.0:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.6.1:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.6.3:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.6.4:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.6.5:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.6.6:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:2.6.7:*:*:*:*:*:*:*

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