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
Published: n/a
Score: 5.5 Medium
EPSS: n/a
KEV: No
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History

Fri, 30 Oct 2026 03:30:00 +0000

Type Values Removed Values Added
First Time appeared Gnome
Gnome epiphany
Vendors & Products Gnome
Gnome epiphany

Fri, 30 Oct 2026 00:30:00 +0000

Type Values Removed Values Added
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
Title epiphany: epiphany: TAR-based .xpi with hard links can overwrite user files during WebExtension install
Weaknesses CWE-59
References
Metrics threat_severity

None

 cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N'}

threat_severity

Moderate

Subscriptions

Gnome Epiphany
cve-icon MITRE

No data.

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-10-24T00:00:00Z

Links: CVE-2026-118599 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-10-30T03:15:06Z

Weaknesses
  • CWE-59

    Improper Link Resolution Before File Access ('Link Following')