CVE-2016-8622: haxx libcurl Heap-based Buffer Overflow

Vulnerability summary

CVE-2016-8622 is a critical (CVSS 9.8) Heap-based Buffer Overflow vulnerability in haxx libcurl. EPSS estimates a 4.67% chance of exploitation in the next 30 days, higher than 91.6% of scored vulnerabilities.

Timeline

1. 31-07-2018
   PublishedVulnerability first disclosed.
2. 15-04-2026
   Last modifiedVulnerability information updated.

Description

The URL percent-encoding decode function in libcurl before 7.51.0 is called `curl_easy_unescape`. Internally, even if this function would be made to allocate a unscape destination buffer larger than 2GB, it would return that new length in a signed 32 bit integer variable, thus the length would get either just truncated or both truncated and turned negative. That could then lead to libcurl writing outside of its heap based buffer.

• CWE-122Heap-based Buffer OverflowA heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
• CWE-190Integer Overflow or WraparoundThe product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
• CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.