mingw: skip symlink type auto-detection for network share targets - #2189
Open
dscho wants to merge 1 commit into
Open
mingw: skip symlink type auto-detection for network share targets#2189dscho wants to merge 1 commit into
dscho wants to merge 1 commit into
Conversation
|
There is an issue in commit 330f153:
|
Member
Author
|
/submit |
|
There is an issue in commit 330f153:
|
On Windows, symbolic links come in two flavors: file symlinks and directory symlinks. Since Git was born on Linux where this distinction does not exist, Git for Windows has to auto-detect the type by looking at the target. When the target does not yet exist at symlink creation time, Git for Windows creates a "phantom" file symlink and later, once checkout is complete, calls `CreateFileW()` on the target to check whether it is actually a directory. If the symlink target is a UNC path (e.g. `\\attacker\share`), this auto-detection triggers an SMB connection to the remote host. Windows performs NTLM authentication by default for such connections, which means a crafted repository can exfiltrate the cloning user's NTLMv2 hash to an attacker-controlled server without any user interaction beyond `git clone -c core.symlinks=true <url>`. There are ways to specify UNC paths that start with only a single backslash (e.g. `\??\UNC\host\share`); All of them do start like that, though, so let's use that as a tell-tale that we should skip the auto-detection in `process_phantom_symlink()`. The symlink is then left as a file symlink (the `mklink` default), and a warning is emitted suggesting the user set the `symlink` gitattribute to `dir` if a directory symlink is needed. When the attribute is already set, auto-detection is never invoked in the first place, so that code path is unaffected. This is the same class of vulnerability as CVE-2025-66413 (GHSA-hv9c-4jm9-jh3x) and follows the same general mitigation pattern that MinTTY adopted for ANSI escape sequences referencing network share paths (GHSA-jf4m-m6rv-p6c5). Note that there are legitimate paths starting with a single backslash that are _not_ network paths: drive-less absolute paths are interpreted as relative to the current working directory's drive. In practice, these are highly uncommon (and brittle, just one working directory change away from breaking). In any case, the only consequence is now that the symlink type of those has to be specified via Git attributes, is all. Reported-by: Justin Lee <jessdhoctor@gmail.com> Addresses: CVE-2026-32631 Assisted-by: Claude Opus 4.6 Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
dscho
force-pushed
the
skip-symlink-detection-for-network-shares
branch
from
July 28, 2026 11:44
330f153 to
19ae3c7
Compare
Member
Author
|
/submit |
|
Submitted as pull.2189.git.1785239196007.gitgitgadget@gmail.com To fetch this version into To fetch this version to local tag |
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
1 participant
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.
This was released as part of Git for Windows v2.53.0(3) already.