Conversation
Cap to 256 KiB. Follow-up to 3ba252e libssh2#1644
vszakats
marked this pull request as draft
July 6, 2026 13:11
This reverts commit 15d4c9d. No CI jobs seem to run this code.
There was a problem hiding this comment.
Pull request overview
This PR hardens the ML-KEM + NIST-P hybrid key exchange path by adding an explicit upper bound check for the remote server’s concatenated public key blob in kex_mlkem_nistp(), aiming to reduce DoS risk from overly large inputs.
Changes:
- Add a maximum-length guard (256 KiB) for
server_public_key_leninkex_mlkem_nistp().
💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.
Comment on lines
+2019
to
2023
| if(server_public_key_len <= mlkem_cipher_len || | ||
| server_public_key_len > (256 * 1024)) { | ||
| ret = ssh2_err(session, LIBSSH2_ERROR_HOSTKEY_INIT, | ||
| "Unexpected mlkemnistp server public key length"); | ||
| goto clean_exit; |
Member
Author
There was a problem hiding this comment.
I don't get this. (except the errmsg, which is wrong, I put in the queue)
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Cap to 256 KiB.
Follow-up to 3ba252e #1644