5.5 Medium

A file overwrite vulnerability exists in Epiphany when installing WebExtension packages from .xpi files.

CVE-2026-118599

A file overwrite vulnerability exists in Epiphany when installing WebExtension packages from .xpi files. In src/webextension/ephy-web-extension-manager.c, decompressxpithread() used libarchive with archivereadsupportformatall() (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 archivewritedisk options (including ARCHIVEEXTRACTPERM), 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/-/mergerequests/2248 (commit 0cc9ab55 — only enable ZIP format support). Upstream: https://gitlab.gnome.org/GNOME/epiphany/-/workitems/2988 Reporter acknowledgment: Fernando Munoz

Assessment

CVSS: 5.5 (v3.1)
Severity: Medium
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 31 October 2026
Last updated: 31 October 2026
Affected: Gnome
Assigner: fedora

CVSS vectorCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

At the source

EUVD (ENISA)

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