#VU26234 Out-of-bounds read in nginx

Vulnerability identifier: #VU26234

Vulnerability risk: Medium

CVSSv4.0: 6.9 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/U:Green]

CVE-ID: N/A

CWE-ID: CWE-125

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
nginx
Server applications / Web servers

Vendor: NGINX

Description

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to a boundary condition when processing rewrite rules with a '\0' character in ngx_http_core_module.c. An attacker with ability to influence a rewrite rule can view memory contents via Location HTTP header.

Successful exploitation of vulnerability requires that an attacker can influence rewrite engine, as demonstrated with OpenResty issue.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

nginx: 0.3.0 - 0.3.61, 0.4.0 - 0.4.14, 0.5.0 - 0.5.38, 0.6.0 - 0.6.1516, 0.7.0 - 0.7.69, 0.8.0 - 0.8.55, 0.9.0 - 0.9.7, 1.0.0 - 1.0.15, 1.1.0 - 1.17.6, 1.2.0 - 1.2.9, 1.3.0 - 1.3.16, 1.4.0 - 1.4.7, 1.5.0 - 1.5.13, 1.6.0 - 1.6.3, 1.7.0 - 1.7.12, 1.8.0 - 1.8.1, 1.9.0 - 1.9.15

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External links
https://hackerone.com/reports/513236
https://seclists.org/oss-sec/2020/q1/113
https://github.com/nginx/nginx/commit/a5895eb502747f396d3901a948834cd87d5fb0c3

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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. However, proof of concept for this vulnerability is available.