Internet Bug Bounty · Report #1997312

CVE-2023-28319: UAF in SSH sha256 fingerprint check

Validstatus

mediumseverity

2upvotes

25 Jun 2023disclosed

Summary

CVE-2023-28319 - UAF in SSH sha256 fingerprint check

VULNERABILITY libcurl offers a feature to verify an SSH server's public key using a SHA 256 hash. When this check fails, libcurl would free the memory for the fingerprint before it returns an error message containing the (now freed) hash.

This flaw risks inserting sensitive heap-based data into the error message that might be shown to users or otherwise get leaked and revealed.

SOLUTION Fixed-in: https://github.com/curl/curl/commit/8e21b1a05f3c0ee098dbcb6c

TIMELINE This issue was reported to the curl project on March 21 2023. We contacted distros @ openwall on May 9, 2023.

curl 8.1.0 was released on May 17 2023, coordinated with the publication of this advisory.

CREDITS Reported-by: Wei Chong Tan Patched-by: Daniel Stenberg Thanks a lot!

Link to full Security Advisory: https://curl.se/docs/CVE-2023-28319.html

How it was found

libcurl offers a feature to verify an SSH server's public key using a SHA 256 hash. When this check fails, libcurl would free the memory for the fingerprint before it returns an error message containing the (now freed) hash.

Affected versions: curl 7.81.0 to and including 8.0.1 Not affected versions: curl < 7.81.0 and curl >= 8.1.0

The original submission can be found here: https://hackerone.com/reports/1913733

Impact

This flaw risks inserting sensitive heap-based data into the error message that might be shown to users or otherwise get leaked and revealed.

This report was disclosed publicly on HackerOne and belongs to its author and the program. See the original