epiphany: TAR-based .xpi with hard links can overwrite user files during WebExtension install
Affects Epiphany 47.0 and later when installing a WebExtension .xpi file. No vendor rating is given; CVSS scores it 5.5 (medium). The fix only enables ZIP format support, and no fixed version is listed.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
Epiphany, the GNOME web browser, is affected when installing WebExtension packages (.xpi files). A maliciously crafted .xpi file can overwrite existing files writable by the user, with attacker-controlled content, when the user installs or opens it.
Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.
Read the original 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
Timeline
- CVE published
- First seen by cve.now
Affected versions
- epiphany
From 47.0
References 4
access.redhat.com
bugzilla.redhat.com
Questions about CVE-2026-118599
What does this mean?
A malicious .xpi file that is really a TAR archive can use hard links to make Epiphany's installer overwrite an existing user-writable file. The attacker controls both the new content and the permission bits of that file.Source: access.redhat.com, gitlab.gnome.org
Am I affected, and how do I check?
Epiphany 47.0 and later are affected on the WebExtension .xpi install path, and only when the victim installs or opens a malicious .xpi file. Check the installed Epiphany version to see whether it falls in the 47.0 or later range.Source: access.redhat.com, gitlab.gnome.org
Is it being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What if there's no patch?
Do not install WebExtensions (.xpi) from untrusted sources. This avoids the install path that the flaw depends on until a fixed build is available.Source: access.redhat.com, gitlab.gnome.org