CVE-2019-16786 Vulnerability Analysis & Exploit Details

CVE-2019-16786
Vulnerability Scoring

7.1
/10
Very High Risk

Highly exploitable, CVE-2019-16786 poses a critical security risk that could lead to severe breaches.

Attack Complexity Details

  • Attack Complexity: High
    Exploits require significant effort and special conditions.
  • Attack Vector: Network
    Vulnerability is exploitable over a network without physical access.
  • Privileges Required: Low
    Some privileges are necessary to exploit the vulnerability.
  • Scope: Changed
    Successful exploitation can impact components beyond the vulnerable component.
  • User Interaction: None
    No user interaction is necessary for exploitation.

CVE-2019-16786 Details

Status: Modified

Last updated: 🕟 21 Nov 2024, 04:31 UTC
Originally published on: 🕚 20 Dec 2019, 23:15 UTC

Time between publication and last update: 1797 days

CVSS Release: version 3

CVSS3 Source

security-advisories@github.com

CVSS3 Type

Secondary

CVSS3 Vector

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

CVE-2019-16786 Vulnerability Summary

CVE-2019-16786: Waitress through version 1.3.1 would parse the Transfer-Encoding header and only look for a single string value, if that value was not chunked it would fall through and use the Content-Length header instead. According to the HTTP standard Transfer-Encoding should be a comma separated list, with the inner-most encoding first, followed by any further transfer codings, ending with chunked. Requests sent with: "Transfer-Encoding: gzip, chunked" would incorrectly get ignored, and the request would use a Content-Length header instead to determine the body size of the HTTP message. This could allow for Waitress to treat a single request as multiple requests in the case of HTTP pipelining. This issue is fixed in Waitress 1.4.0.

Assessing the Risk of CVE-2019-16786

Access Complexity Graph

The exploitability of CVE-2019-16786 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2019-16786

This vulnerability, CVE-2019-16786, requires a high level of attack complexity and low privileges, making it difficult but not impossible to exploit. Organizations should ensure robust security configurations to mitigate risks.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2019-16786, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2019-16786, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: High
    Exploiting CVE-2019-16786 can result in unauthorized access to sensitive data, severely compromising data privacy.
  • Integrity: Low
    Exploiting CVE-2019-16786 may cause minor changes to data without severely impacting its accuracy.
  • Availability: None
    CVE-2019-16786 does not impact system availability.

Exploit Prediction Scoring System (EPSS)

The EPSS score estimates the probability that this vulnerability will be exploited in the near future.

EPSS Score: 0.336% (probability of exploit)

EPSS Percentile: 71.51% (lower percentile = lower relative risk)
This vulnerability is less risky than approximately 28.489999999999995% of others.

CVE-2019-16786 References

External References

CWE Common Weakness Enumeration

CWE-444

CAPEC Common Attack Pattern Enumeration and Classification

  • HTTP Response Smuggling CAPEC-273 An adversary manipulates and injects malicious content in the form of secret unauthorized HTTP responses, into a single HTTP response from a vulnerable or compromised back-end HTTP agent (e.g., server). See CanPrecede relationships for possible consequences. Modification/manipulation of HTTP message headers, request-line and body parameters to disrupt and interfere in the interpretation and parsing of HTTP message lengths/boundaries for consecutive HTTP messages by HTTP agents in a HTTP chain or network path.
  • HTTP Request Smuggling CAPEC-33 An adversary abuses the flexibility and discrepancies in the parsing and interpretation of HTTP Request messages using various HTTP headers, request-line and body parameters as well as message sizes (denoted by the end of message signaled by a given HTTP header) by different intermediary HTTP agents (e.g., load balancer, reverse proxy, web caching proxies, application firewalls, etc.) to secretly send unauthorized and malicious HTTP requests to a back-end HTTP agent (e.g., web server). See CanPrecede relationships for possible consequences. Modification/manipulation of HTTP message headers, request-line and body parameters to disrupt and interfere in the interpretation and parsing of HTTP message lengths/boundaries for consecutive HTTP messages by HTTP agents in a HTTP chain or network path.

Vulnerable Configurations

  • cpe:2.3:a:agendaless:waitress:0.1:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.1:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.2:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.2:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.3:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.3:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.4:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.4:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.5:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.5:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.6:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.6:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.6.1:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.6.1:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.7:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.7:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.8:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.8:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.8.1:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.8.1:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.8.2:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.8.2:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.8.3:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.8.3:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.8.4:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.8.4:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.8.5:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.8.5:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.8.6:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.8.6:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.8.7:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.8.7:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.8.8:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.8.8:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.8.9:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.8.9:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.8.10:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.8.10:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.8.11:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.8.11:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:0.9.0:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:0.9.0:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:1.0.0:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:1.0.0:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:1.0.1:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:1.0.1:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:1.0.2:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:1.0.2:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:1.1.0:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:1.1.0:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:1.2.0:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:1.2.0:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:1.2.1:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:1.2.1:*:*:*:*:*:*:*
  • cpe:2.3:a:agendaless:waitress:1.3.0:*:*:*:*:*:*:*
    cpe:2.3:a:agendaless:waitress:1.3.0:*:*:*:*:*:*:*
  • cpe:2.3:a:oracle:communications_cloud_native_core_network_function_cloud_native_environment:1.10.0:*:*:*:*:*:*:*
    cpe:2.3:a:oracle:communications_cloud_native_core_network_function_cloud_native_environment:1.10.0:*:*:*:*:*:*:*
  • cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
    cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
  • cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*
    cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*
  • cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*
    cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*
  • cpe:2.3:a:redhat:openstack:15:*:*:*:*:*:*:*
    cpe:2.3:a:redhat:openstack:15:*:*:*:*:*:*:*

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