CVE-2020-15811
An issue was discovered in Squid before 4.13 and 5.x before 5.0.4. Due to incorrect data validation, HTTP Request Splitting attacks may succeed against HTTP and HTTPS traffic. This leads to cache poisoning. This allows any client, including browser scripts, to bypass local security and poison the browser cache and any downstream caches with content from an arbitrary source. Squid uses a string search instead of parsing the Transfer-Encoding header to find chunked encoding. This allows an attacker to hide a second request inside Transfer-Encoding: it is interpreted by Squid as chunked and split out into a second request delivered upstream. Squid will then deliver two distinct responses to the client, corrupting any downstream caches.
Vulnerability Summary
CVSS v3 Score
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
CVSS v2 Score
AV:N/AC:L/Au:S/C:N/I:P/A:N
EPSS Score (Exploitation Probability)
This vulnerability has a 4.23% probability of being exploited in the next 30 days, ranking higher than 90% of all scored CVEs.
CWE Classification
Related Vulnerabilities
Same Weakness Type(CWE-697)
iccDEV provides a set of libraries and tools that allow for the interaction, manipulation, and application of International Color Consortium (ICC) color management profiles. Versions prior to 2.3.1.2 have a Type Confusion vulnerability in `CIccTag:IsTypeCompressed()`. This vulnerability affects users of the iccDEV library who process ICC color profiles. Version 2.3.1.2 contains a patch. No known workarounds are available.
The SureTriggers: All-in-One Automation Platform plugin for WordPress is vulnerable to an authentication bypass leading to administrative account creation due to a missing empty value check on the 'secret_key' value in the 'autheticate_user' function in all versions up to, and including, 1.0.78. This makes it possible for unauthenticated attackers to create administrator accounts on the target website when the plugin is installed and activated but not configured with an API key.
Softaculous Webuzo contains an authentication bypass vulnerability through the password reset functionality. Remote, anonymous attackers can exploit this vulnerability to gain full server access as the root user.
Cacti provides an operational monitoring and fault management framework. Prior to version 1.2.27, Cacti calls `compat_password_hash` when users set their password. `compat_password_hash` use `password_hash` if there is it, else use `md5`. When verifying password, it calls `compat_password_verify`. In `compat_password_verify`, `password_verify` is called if there is it, else use `md5`. `password_verify` and `password_hash` are supported on PHP < 5.5.0, following PHP manual. The vulnerability is in `compat_password_verify`. Md5-hashed user input is compared with correct password in database by `$md5 == $hash`. It is a loose comparison, not `===`. It is a type juggling vulnerability. Version 1.2.27 contains a patch for the issue.
Owncast is an open source, self-hosted, decentralized, single user live video streaming and chat server. In versions 0.1.2 and prior, a lenient CORS policy allows attackers to make a cross origin request, reading privileged information. This can be used to leak the admin password. Commit 9215d9ba0f29d62201d3feea9e77dcd274581624 fixes this issue.
Similar SeverityMEDIUM
In OpenStack Nova before 33.0.2, the server create API does not strip certain hint data. The resulting instance has no Placement allocation.
Improper access control in the social login connection endpoint in Devolutions Server 2026.2.5 allows an authenticated vault member to enumerate social login entry metadata to which they are not authorized via a crafted API request.
Improper access control in Devolutions Server 2026.2.5, 2026.1.21 allows an authenticated user to access attachments via folder duplication with inherited permissions.
A flaw was found in GnuTLS. The `gnutls_pkcs11_token_set_pin` function, used for changing the Security Officer PIN, can lead to a use-after-free vulnerability. This occurs when an attacker attempts to change the PIN with a NULL old PIN for a token that lacks a protected authentication path.
A flaw was found in the GNOME localsearch (previously known as tracker-miners) MP3 Extractor `tracker-extract-mp3` component. A remote attacker could exploit this heap buffer overflow vulnerability by providing a specially crafted MP3 file containing malformed ID3 tags. This incorrect length calculation during the parsing of performer tags can lead to a read beyond the allocated buffer, potentially causing a Denial of Service (DoS) due to a crash or enabling information disclosure.
Learn More
View this score breakdown or calculate a custom score
Learn how severity scores are calculated and what they mean
Best practices for deciding which vulnerabilities to address first
Essential guide to Common Vulnerabilities and Exposures