CVE-2026-44950
fs_read_glyphs() heap buffer overflow via cumulative glyph data overflow in libXfont2
No known exploitation. EPSS puts it in the 36th percentile. No fix published yet.
What to do
No fixed build or workaround is published yet. Limit exposure and watch for a patch.
What it is
From the CVE record
fs_read_glyphs() in the libXfont2 font-server client (src/fc/fserve.c) copies each glyph's bitmap into a single buffer. Existing checks validates only that the source slice (position, length) lies within the source bitmap buffer. It does not check whether the running destination cursor has exceeded the allocation. A malicious font server can send overlapping source offsets -- for example 1000 glyphs each referencing {position:0, length:64} with nbytes=64. Each individual source range passes the existing validation, but the cumulative writes total 64000 bytes into a 64-byte destination buffer. This is a heap buffer overflow with attacker-controlled content.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
0.4% chance of exploitation activity in the next 30 days, which ranks it in the 36th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
7 events over 33 days, from the signal feeds we watch.
- Publishedweakness classified, att&ck mapped, record updated, record updated, record updated
- OpenVAS check added
Affected products
- Container suse/kiosk/tigervnc-x11vnc:1.14-63.8Operating Systems / linux-distro
- Container suse/kiosk/xorg:21.1-83.7Operating Systems / linux-distro
- Image SLES15-SP6-SAPOperating Systems / linux-distro
- Image SLES15-SP6-SAP-AzureOperating Systems / linux-distro
- Image SLES15-SP6-SAP-Azure-3POperating Systems / linux-distro
- Image SLES15-SP6-SAP-BYOSOperating Systems / linux-distro
- Image SLES15-SP6-SAP-BYOS-AzureOperating Systems / linux-distro
- Image SLES15-SP6-SAP-BYOS-EC2Operating Systems / linux-distro
And 71 more affected products. See all after sign-in
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Scored 9.0 by NVD.
How it is reached
- Attack Vector NetworkExploitable remotely over the network without any special conditions
- Attack Complexity HighRequires specific conditions like a race condition or non-default configuration
- Privileges Required NoneNo authentication required — anyone can exploit this
- User Interaction NoneNo user interaction needed — fully automated exploitation
Scope
- Scope ChangedThe exploit can affect other components (e.g. sandbox escape, host compromise from VM)
Impact if exploited
- Confidentiality HighTotal information disclosure — all data in the component is compromised
- Integrity HighTotal loss of integrity — attacker can modify any data in the component
- Availability HighTotal denial of service — the component is completely unavailable
Weaknesses
ATT&CK techniques
Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.
- Privilege EscalationT1068Exploitation for Privilege Escalationhigh confidence
Sources
References in the record
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