#VU40728 Improper access control in Symfony - CVE-2015-4050

Vulnerability identifier: #VU40728

Vulnerability risk: Medium

CVSSv4.0: 2.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2015-4050

CWE-ID: CWE-284

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Symfony
Web applications / CMS

Vendor: SensioLabs

Description

The vulnerability allows a remote non-authenticated attacker to manipulate data.

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.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Symfony: 2.3.19 - 2.6.7

---

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

---

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.