This flaw makes curl overflow a heap based buffer in the SOCKS5 proxy
handshake.
When curl is asked to pass along the host name to the SOCKS5 proxy to allow
that to resolve the address instead of it getting done by curl itself, the
maximum length that host name can be is 255 bytes.
If the host name is detected to be longer, curl switches to local name
resolving and instead passes on the resolved address only. Due to this bug,
the local variable that means "let the host resolve the name" could get the
wrong value during a slow SOCKS5 handshake, and contrary to the intention,
copy the too long host name to the target buffer instead of copying just the
resolved address there.
The target buffer being a heap based buffer, and the host name coming from the
URL that curl has been told to operate with.
When curl retrieves an HTTP response, it stores the incoming headers so that
they can be accessed later via the libcurl headers API.
However, curl did not have a limit in how many or how large headers it would
accept in a response, allowing a malicious server to stream an endless series
of headers and eventually cause curl to run out of heap memory.
Why is Microsoft republishing a CVE from 2013?
We are republishing CVE-2013-3900 in the Security Update Guide to update the Security Updates table and to inform customers that the EnableCertPaddingCheck is available in all currently supported versions of Windows 10 and Windows 11. While the format is different from the original CVE published in 2013, except for clarifications about how to configure the EnableCertPaddingCheck registry value, the information herein remains unchanged from the original text published on December 10, 2013,
Microsoft does not plan to enforce the stricter verification behavior as a default functionality on supported releases of Microsoft Windows. This behavior remains available as an opt-in feature via reg key setting, and is available on supported editions of Windows released since December 10, 2013. This includes all currently supported versions of Windows 10 and Windows 11. The supporting code for this reg key was incorporated at the time of release for Windows 10 and Windows 11, so no security update is required; however, the reg key must be set. See the Security Updates table for the list of affected software.
Vulnerability Description
A remote code execution vulnerability exists in the way that the WinVerifyTrust function handles Windows Authenticode signature verification for portable executable (PE) files. An anonymous attacker could exploit the vulnerability by modifying an existing signed executable file to leverage unverified portions of the file in such a way as to add malicious code to the file without invalidating the signature. An attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.
If a user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
Exploitation of this vulnerability requires that a user or application run or install a specially crafted, signed PE file. An attacker could modify an... See more at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2013-3900