A heap use-after-free was found in str_to_reg() in Vim < 9.1.1115 ================================================================== Date: 16.02.2025 Severity: Medium CVE: *not yet assigned CWE: Use-after-free (CWE-416)
Vim allows to redirect screen messages using the `:redir` ex command to register, variables and files. It also allows to show the contents of registers using the `:registers` or `:display` ex command. When redirecting the output of `:display` to a register, Vim will free the register content before storing the new content in the register. Now when redirecting the `:display` command to a register that is being displayed, Vim will free the content while shortly afterwards trying to access it, which leads to a use-after-free. Vim pre 9.1.1115 checks in the ex_display() function, that it does not try to redirect to a register while displaying this register at the same time. However this check is not complete, and so Vim does not check the `+` and `*` registers (which typically donate the X11/clipboard registers, and when a clipboard connection is not possible will fall back to use register 0 instead. In Patch 9.1.1115 Vim will therefore skip outputting to register zero when trying to redirect to the clipboard registers `*` or `+`. Impact is medium since this is a rather unusual situation and a user must explicitly run this command. The Vim project would like to thank github user @fizz-is-on-the-way for reporting this issue. The issue has been fixed as of Vim patch v9.1.1115 References: https://github.com/vim/vim/commit/c0f0e2380e5954f4a52a131bf6b8 https://github.com/vim/vim/security/advisories/GHSA-63p5-mwg2-787v Thanks, Christian
