CVE-2026-56003
Heap overflow in libXfont2 PCF parsing allows code execution in X server.
Is CVE-2026-56003 being exploited?
Not confirmed. CVE-2026-56003 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.40% probability of exploitation in the next 30 days.
How severe is CVE-2026-56003?
CVE-2026-56003 is rated High with a CVSS score of 8.5. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-56003?
Yes. A fix has been recorded for CVE-2026-56003. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-56003 affect?
CVE-2026-56003 affects libXfont2 < 2.0.8, X.Org X Server, Linux/BSD systems running X11 desktops. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-56003?
Upgrade libXfont2 to 2.0.8+, restrict untrusted X client access, apply vendor updates.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Authenticated X clients can trigger a heap overflow parsing PCF files to execute arbitrary code in the X server, risking system compromise and possible privilege escalation.
Patch when possible
- affected< 2.0.8
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.