# CVE-2026-78376: Webkitgtk: use-after-free of jscvalue function parameters

Status: published. Published: 2026-08-24. Updated: 2026-11-02.

A flaw was found in WebKitGTK. Processing malicious web content can cause a use-after-free issue due to improper memory handling and result in memory corruption.

## Remediation

- workaround: Do not process or load untrusted web content with WebKitGTK.

In Red Hat Enterprise Linux 7, the following packages require WebKitGTK4: evolution-data-server, glade, gnome-boxes, gnome-initial-setup, gnome-online-accounts, gnome-shell, shotwell, sushi and yelp.

This vulnerability can only be exploited when these packages are installed in the system and being used via a graphical interface to process untrusted web content, via GNOME for example. In gnome-shell, the vulnerability can be exploited by an attacker from the local network without user interaction.

To mitigate this vulnerability, consider removing these packages. Note that some of these packages are required by GNOME, removing them will also remove GNOME and other packages, breaking functionality. However, the server can still be used via the terminal interface.

Additionally, WebKitGTK3 is not required by any package. Therefore, it can be removed without consequences or break of functionality. (source: CNA: redhat)

## Affected products and versions

- WebKit / WebKit (webkit): ≥ 2.21.1; < * (affected, semver). Source: CNA: redhat
- WebKitGTK / WebKitGTK (webkitgtk): ≥ 2.21.1; < * (affected, semver). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 Extended Lifecycle Support (webkitgtk4): ≥ 0:2.54.0-1.el7_9; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (webkit2gtk3): ≥ 0:2.54.0-1.el8_10; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support (webkit2gtk3): ≥ 0:2.54.0-1.el8_6; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On (webkit2gtk3): ≥ 0:2.54.0-1.el8_6; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.8 Telecommunications Update Service (webkit2gtk3): ≥ 0:2.54.0-1.el8_8; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions (webkit2gtk3): ≥ 0:2.54.0-1.el8_8; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (webkit2gtk3): ≥ 0:2.54.0-1.el9_8; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions (webkit2gtk3): ≥ 0:2.54.0-1.el9_2; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions (webkit2gtk3): ≥ 0:2.54.0-1.el9_4; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.6 Extended Update Support (webkit2gtk3): ≥ 0:2.54.0-1.el9_6; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (webkitgtk): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (webkitgtk3): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 8.8 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.47% as of 2026-11-01; percentile 40.56%

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-416

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/errata/RHSA-2026:69098 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:74084 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:89821 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:89822 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:91631 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:92216 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:92339 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:93435 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-78376 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2521858 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://github.com/WebKit/WebKit/pull/72142 (CNA: redhat)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-78376; retrieved 2026-11-02; source updated 2026-11-02

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-78376; retrieved 2026-11-02; source updated Not reported

Revision: 5b4f877c68715ef80d976a209802e86027dd401185625a456348f142241c923d

Canonical: https://y2.dev/cve/CVE-2026-78376