CVE-2016-9586 log

Source	CVE Red Hat MITRE NVD Debian Ubuntu SUSE Alpine Mageia CVE Details CIRCL Bugs Arch Linux Red Hat Gentoo SUSE GitHub Lists oss-security full-disclosure bugtraq Misc GitHub code web search
Severity	Medium
Remote	Yes
Type	Arbitrary code execution
Description	libcurl's implementation of the printf() functions triggers a buffer overflow when doing a large floating point output. The bug occurs when the conversion outputs more than 255 bytes. The flaw happens because the floating point conversion is using system functions without the correct boundary checks. The functions have been documented as deprecated for a long time and users are discouraged from using them in "new programs" as they are planned to get removed at a future point. But as the functions are present and there's nothing preventing users from using them, we expect there to be a certain amount of existing users in the wild. If there are any application that accepts a format string from the outside without necessary input filtering, it could allow remote attacks.

Group	Package	Affected	Fixed	Severity	Status	Ticket
AVG-117	lib32-libcurl-gnutls	7.51.0-1	7.52.1-1	Medium	Fixed	FS#52247
AVG-116	lib32-libcurl-compat	7.51.0-1	7.52.1-1	Medium	Fixed	FS#52247
AVG-115	lib32-curl	7.51.0-1	7.52.1-1	Medium	Fixed	FS#52247
AVG-114	libcurl-gnutls	7.51.0-1	7.52.1-1	Medium	Fixed	FS#52247
AVG-113	libcurl-compat	7.51.0-1	7.52.1-1	Medium	Fixed	FS#52247
AVG-112	curl	7.51.0-1	7.52.1-1	Medium	Fixed	FS#52247

Date	Advisory	Group	Package	Severity	Type
03 Jan 2017	ASA-201701-9	AVG-115	lib32-curl	Medium	multiple issues
03 Jan 2017	ASA-201701-8	AVG-114	libcurl-gnutls	Medium	multiple issues
03 Jan 2017	ASA-201701-7	AVG-113	libcurl-compat	Medium	multiple issues
03 Jan 2017	ASA-201701-11	AVG-117	lib32-libcurl-gnutls	Medium	multiple issues
03 Jan 2017	ASA-201701-10	AVG-116	lib32-libcurl-compat	Medium	multiple issues
27 Dec 2016	ASA-201612-22	AVG-112	curl	Medium	multiple issues

References
https://curl.haxx.se/docs/adv_20161221A.html

Notes
This flaw is present in the curl_printf (curlx_printf) family of functions, which are not used by curl but are exposed from libcurl. To be exposed, third-party code would need to be using these long-deprecated functions, with a floating-point specifier and user-controlled (floating-point) input. The overflow itself is of a 256-byte stack-allocated buffer, when the decimal expansion of the float exceeds that by up to 70 bytes. Beyond about 16 digits for a double, the decimal expansion is effectively random so the attacker has very little control over precisely what bytes are written.

Notes

This flaw is present in the curl_*printf (curlx_*printf) family of functions, which are not used by curl but are exposed from libcurl.
To be exposed, third-party code would need to be using these long-deprecated functions, with a floating-point specifier and user-controlled (floating-point) input. The overflow itself is of a 256-byte stack-allocated buffer, when the decimal expansion of the float exceeds that by up to 70 bytes. Beyond about 16 digits for a double, the decimal expansion is effectively random so the attacker has very little control over precisely what bytes are written.