CVE-2023-48706

What it actually does

Heap use-after-free triggered when the first :s command uses a sub-replace-special atom that causes a recursive :s call to free memory later accessed by the original command.

Why it matters to the business

Local users can crash Vim or achieve limited memory corruption on affected systems; because the issue is over two years old and an exploit is publicly available, unpatched installations remain exposed until upgraded.

How an attack unfolds

An attacker supplies a crafted :s substitution containing a sub-replace-special atom, executes it as the very first :s command, and relies on the recursive call to free memory that the outer command subsequently accesses, potentially leading to a crash or controlled memory state.

How to fix it

Upgrade vim/vim to the commit 26c11c56888d01e298cd8044caf860f3c26f57bb (version 9.0.2121 or later). Rebuild and redeploy any packages that embed the vulnerable Vim source.

How to confirm the fix worked

Confirm the installed Vim binary reports version 9.0.2121 or later; attempt the original :s reproducer and verify it no longer triggers a use-after-free or crash.

Typical attack path

1. Craft a :s command that includes a sub-replace-special atom
2. Ensure it is the first :s command executed in the Vim session
3. Trigger the recursive substitution path
4. Observe or leverage the resulting use-after-free condition

How to detect it

Review system logs for Vim segmentation faults or heap-error messages during substitution operations; inspect command history files for unusual :s patterns on systems where Vim is used interactively.

What your security team should do

• Immediately update all Vim installations to the fixed commit
• Scan build pipelines and container images for the vulnerable vim source
• Monitor public exploit repositories for working PoCs given the ExploitAvailable maturity
• Restrict interactive Vim usage on high-value systems until patched