CVE-2026-55999
An attacker can exploit multiple vulnerabilities in X.Org X11 and Xwayland to cause a denial of service or potentially execute arbitrary program code.
CSIRTS triage
- What
- Multiple vulnerabilities allow an attacker to cause denial of service or execute arbitrary code.
- Who is affected
- Deployments of X.Org X11 and Xwayland are affected.
- Urgency
- Remediation is urgent due to the high severity and potential for exploitation.
- Action
- Apply available patches for X.Org X11 and Xwayland.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.21% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 11% of all EPSS-scored CVEs.
Advisory coverage (3)
- high[NEW] [high] X.Org X11 and Xwayland: Multiple vulnerabilities allow code execution and DoScert-bund · 2026-07-09
- highCVE-2026-55999: Local attackers with a X connection able to provide PCX fonts to the X server xorg-server befo…nvd · 2026-07-08
- highCVE-2026-55999: xorg-server / xwayland glamor font atlas Heap Buffer Overflowmsrc · 2026-07-02
External references
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[](https://www.csirts.com/cve/CVE-2026-55999)