CVE-2016-8622
URL unescape heap overflow via integer truncation
Project curl Security Advisory, November 2, 2016 - Permalink
VULNERABILITY
The URL percent-encoding decode function in libcurl is called
curl_easy_unescape. Internally, even if this function would
be made to allocate a 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.
This can be triggered by a user on a 64bit system if the user can send in a custom (very large) URL to a libcurl using program.
INFO
The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2016-8622 to this issue.
CWE-122: Heap-based Buffer Overflow
Severity: Medium
AFFECTED VERSIONS
This flaw exists in the following curl versions
- Affected versions: curl 7.24.0 to and including 7.50.3
- Not affected versions: curl < 7.24.0 and curl >= 7.51.0
- Introduced-in: https://github.com/curl/curl/commit/75ca568fa1
libcurl is used by many applications, but not always advertised as such!
SOLUTION
In version 7.51.0, the parser function is fixed.
RECOMMENDATIONS
We suggest you take one of the following actions immediately, in order of preference:
A - Upgrade curl and libcurl to version 7.51.0
B - Apply the patch to your version and rebuild
TIMELINE
It was first reported to the curl project on September 23 by Cure53.
We contacted distros@openwall on October 19.
curl 7.51.0 was released on November 2 2016, coordinated with the publication of this advisory.
CREDITS
- Reported-by: Cure53
- Patched-by: Daniel Stenberg
his vulnerability was found during a Secure Open Source audit performed by Cure53.