# CVE-2026-108976: GNU Emacs command injection via TRAMP user field in filename

Source: https://junglewise.ai/threats/cve-2026-108976-gnu-emacs-before-31-2-and-tramp-through-2-8-2-allows-os-command  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-11. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-108976 · Severity: high · CVSS 7.8 · Published 2026-10-11

GNU Emacs and TRAMP, which provide remote file editing capabilities over SSH and other protocols, fail to properly validate filenames. An attacker can craft a specially formatted filename that executes arbitrary shell commands on the local system when the file is accessed, even without a successful remote connection—a zero-click attack that requires only opening or checking a malicious file path.

Technologies: [Gnu Emacs](https://junglewise.ai/threats/technologies/emacs). Vendors: [Gnu](https://junglewise.ai/threats/vendors/gnu).

## Quick answers

**Is CVE-2026-108976 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-108976 being exploited in the wild.

**How severe is CVE-2026-108976?** High severity, with a CVSS score of 7.8, published 11 October 2026.

**Which products and versions are affected?** Gnu Emacs before 31.2; Gnu TRAMP through 2.8.2.

**Is there a fix for CVE-2026-108976?** Yes: fixed in GNU Emacs 31.2; GNU TRAMP 2.8.3 or later. Until then: Restrict access to untrusted files and directories, especially symlinks with TRAMP-formatted targets, or disable TRAMP if remote file editing is not required. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-108976 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-108976?** Check whether you run Gnu Emacs or Gnu TRAMP at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in GNU Emacs 31.2; GNU TRAMP 2.8.3 or later

Restrict access to untrusted files and directories, especially symlinks with TRAMP-formatted targets, or disable TRAMP if remote file editing is not required.

## Technical details

The vulnerability exists in TRAMP's tramp-user-regexp, which does not adequately restrict characters in the user field of file paths like /ssh:user@host:/path. Characters such as $, (, ), ;, and backticks are permitted, allowing shell metacharacter injection. When tramp-maybe-open-connection builds a login command by unquoted concatenation of arguments, these payloads execute in the local shell spawned for connection setup. Additionally, tramp-build-prefix-regexp uses line-anchoring instead of string-anchoring, allowing embedded TRAMP paths after a newline to be dispatched to TRAMP handlers, exploitable via symlink targets or directory structures.

## Affected products

- GNU Emacs before 31.2
- GNU TRAMP through 2.8.2

## Timeline

- 2026-08-21: disclosed: oss-security mailing list disclosure by Sean Whitton
- 2026-10-11: advisory: CVE-2026-108976 published

## References

- [https://ftp.gnu.org/gnu/tramp/tramp-2.8.2.tar.gz](https://ftp.gnu.org/gnu/tramp/tramp-2.8.2.tar.gz)
- [https://www.openwall.com/lists/oss-security/2026/08/21/1](https://www.openwall.com/lists/oss-security/2026/08/21/1)

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