Allele Security Alert
ASA-2019-00306
Identifier(s)
ASA-2019-00306, CVE-2019-5436
Title
TFTP receive buffer overflow
Vendor(s)
the Curl project
Product(s)
curl
Affected version(s)
libcurl 7.19.4 to and including 7.64.1
Fixed version(s)
libcurl 7.65.0
Proof of concept
Unknown
Description
libcurl contains a heap buffer overflow in the function (‘tftp_receive_packet()’) that recevives data from a TFTP server. It calls ‘recvfrom()’ with the default size for the buffer rather than with the size that was used to allocate it. Thus, the content that might overwrite the heap memory is entirely controlled by the server.
The flaw exists if the user selects to use a “blksize” of 504 or smaller (default is 512). The smaller size that is used, the larger the possible overflow becomes.
Users chosing a smaller size than default should be rare as the primary use case for changing the size is to make it larger.
Technical details
Unknown
Credits
l00p3r
Reference(s)
TFTP receive buffer overflow
https://curl.haxx.se/docs/CVE-2019-5436.html
– Chad Monroe provided the new CURLOPT_TFTP_BLKSIZE option that allows an app
https://github.com/curl/curl/commit/0516ce7786e95
tftp: use the current blksize for recvfrom()
https://github.com/curl/curl/commit/2576003415625d7b5f0e390902f8097830b82275
[SECURITY ADVISORY] curl: TFTP receive buffer overflow
https://seclists.org/oss-sec/2019/q2/124
CVE-2019-5436
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-5436
CVE-2019-5436
https://nvd.nist.gov/vuln/detail/CVE-2019-5436
If there is any error in this alert or you wish a comprehensive analysis, let us know.
Last modified: May 24, 2019