CVE-2026-118599
epiphany: TAR-based .xpi with hard links can overwrite user files during WebExtension install
- State
- Published
- Severity
- 5.5 Medium
- Published
- Oct 31, 2026
- Updated
- Oct 31, 2026
- Reserved
- Oct 28, 2026
Description
A file overwrite vulnerability exists in Epiphany when installing WebExtension packages from .xpi files.
In src/webextension/ephy-web-extension-manager.c, decompress_xpi_thread() used libarchive with archive_read_support_format_all() (and filters), so the installer did not require a real ZIP. A TAR file named *.xpi was extracted. TAR supports hard-link entry types; with Epiphany's archive_write_disk options (including ARCHIVE_EXTRACT_PERM), a crafted hard-link target can cause an attacker-chosen existing user-writable file to be truncated and overwritten with attacker-controlled content and mode bits, without a dedicated warning dialog, when the user installs or opens the crafted .xpi.
This is related to but separate from the ZIP-slip path traversal fixed as CVE-2026-77679 (#2922 / MR !2143).
Requirements: the victim must install or open a malicious WebExtension (.xpi).
Affected: Epiphany >= 47.0 (WebExtension XPI install path). Fixed: https://gitlab.gnome.org/GNOME/epiphany/-/merge_requests/2248 (commit 0cc9ab55 — only enable ZIP format support). Upstream: https://gitlab.gnome.org/GNOME/epiphany/-/work_items/2988 Reporter acknowledgment: Fernando Munoz
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 5.5 Medium | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N | fedora |
Weaknesses
- CWE-59 Improper Link Resolution Before File Access ('Link Following')
Affected Products
| Product | Versions |
|---|---|
EpiphanyGNOME |
|
References
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