CyberSecBulletin
CVE-2026-44950NVD status: Awaiting Analysis

Container suse/kiosk/tigervnc-x11vnc:1.14-63.8: Heap-based Buffer Overflow

Published Updated By the CyberSecBulletin desk

CVE-2026-44950 is a critical-severity heap-based buffer overflow vulnerability in Container suse/kiosk/tigervnc-x11vnc:1.14-63.8 from SUSE, with a CVSS 3.1 base score of 9.0 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 2.0.3-150000.3.6.1 as the first without the flaw, so updating Container suse/kiosk/tigervnc-x11vnc:1.14-63.8 to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.26% chance of exploitation within 30 days, which is low compared with other CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Container suse/kiosk/tigervnc-x11vnc:1.14-63.8 to 2.0.3-150000.3.6.1 or a later version.
  2. Update Container suse/kiosk/xorg:21.1-83.7 to 2.0.3-150000.3.6.1 or a later version.
  3. Update Image SLES15-SP6-SAP to 2.0.3-150000.3.6.1 or a later version.
  4. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
SUSEContainer suse/kiosk/tigervnc-x11vnc:1.14-63.8? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEContainer suse/kiosk/xorg:21.1-83.7? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAP? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAP-Azure? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAP-Azure-3P? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAP-BYOS? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAP-BYOS-Azure? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAP-BYOS-EC2? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAP-BYOS-GCE? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAP-EC2? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAP-GCE? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAP-Hardened? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAP-Hardened-Azure? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAP-Hardened-BYOS? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAP-Hardened-BYOS-Azure? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAP-Hardened-BYOS-EC2? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAP-Hardened-BYOS-GCE? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAP-Hardened-EC2? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAP-Hardened-GCE? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAPCAL? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAPCAL-Azure? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAPCAL-EC2? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP6-SAPCAL-GCE? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP7-SAP-Azure? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1
SUSEImage SLES15-SP7-SAP-Azure-3P? up to, but not including, 2.0.3-150000.3.6.12.0.3-150000.3.6.1

Version data comes from the organisation that assigned the CVE; 35 further products are omitted here. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
ChangedThe attack can reach beyond the vulnerable component into other systems.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H. Scored by CNA (suse.de).

Scoring systemScoreSeverityScored by
CVSS 4.09.5CriticalCNA (suse.de)
CVSS 3.19.0CriticalCNA (suse.de)

Official description

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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Heap-based Buffer Overflow

The product writes past the end of a buffer that was allocated on the heap.

How developers prevent this class of flaw

  • Pre-design: Use a language or compiler that performs automatic bounds checking.
  • Use an abstraction library to abstract away risky APIs. Not a complete solution.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Heap-based Buffer Overflow vulnerabilities (CWE-122)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).

References

Other vulnerabilities in Container suse/kiosk/tigervnc-x11vnc:1.14-63.8

All Container suse/kiosk/tigervnc-x11vnc:1.14-63.8 vulnerabilities

Recent Heap-based Buffer Overflow vulnerabilities

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