Security Experts:

Information Disclosure, DoS Flaws Patched in libcurl

The developers of the popular multiprotocol data transfer library libcurl informed users on Wednesday that the latest version addresses two vulnerabilities.

Libcurl is a free and highly portable file transfer library that supports roughly two dozen protocols and various features. The libcurl website lists more than 250 organizations that use the library in their products, including Adobe, Apple, the BBC, BMW, Broadcom, Cisco, Electronic Arts, Facebook, Google, Intel, Mozilla, Samsung, Sony, VMware and several cybersecurity firms.

The latest Libcurl release, version 7.58.0, patches a total of 82 bugs, including two vulnerabilities that can lead to information disclosure or a denial-of-service (DoS) condition.

One of the security holes, tracked as CVE-2018-1000007, can lead to authentication data getting leaked to third parties.

“When asked to send custom headers in its HTTP requests, libcurl will send that set of headers first to the host in the initial URL but also, if asked to follow redirects and a 30X HTTP response code is returned, to the host mentioned in URL in the Location: response header value,” developers said in an advisory.

“Sending the same set of headers to subsequest hosts is in particular a problem for applications that pass on custom Authorization: headers, as this header often contains privacy sensitive information or data that could allow others to impersonate the libcurl-using client's request,” they added.

This vulnerability has existed in the libcurl code for a long time. “It existed in the first commit we have recorded in the project,” developers noted.

The second flaw, identified as CVE-2018-1000005, has been described as an out-of-bounds read issue that can lead to a DoS condition or information disclosure.

“The problem is that the code that creates HTTP/1-like headers from the HTTP/2 trailer data once appended a string like ‘:’ to the target buffer, while this was recently changed to ‘: ‘ (a space was added after the colon) but the associated math wasn't updated correspondingly,” developers explained. “When accessed, the data is read out of bounds and causes either a crash or that the (too large) data gets passed to the libcurl callback.”

This vulnerability only affects libcurl versions 7.49.0 through 7.57.0.

CVE-2018-1000007 was reported to cURL developers on January 18, while CVE-2018-1000005 was brought to their attention on January 10. Developers said they had not been aware of any attempts to exploit these flaws.

Various Linux distributions are also working on pushing out updates that patch the flaws.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.