CyberSecBulletin
CVE-2026-59679NVD status: Awaiting Analysis

Container suse/kiosk/tigervnc-x11vnc:1.14-63.8: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-59679 is a critical-severity out-of-bounds write 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 4.09.2CriticalCNA (suse.de)
CVSS 3.19.0CriticalCNA (suse.de)

Official description

fs_read_glyphs() in the libXfont2 font-server client (src/fc/fserve.c) indexes the per-character encoding[] array using num_chars from the FS_QueryXBitmaps16 reply, but that array was allocated with a size derived from num_extents in the separate FS_QueryXExtents16 reply. The two CARD32 fields are never cross-checked. A malicious or compromised font server can send a small num_extents (e.g. 1) in the extents reply, then a large num_chars (e.g. 100000) in the bitmaps reply. This causes attacker-controlled out-of-bounds heap read and writes.

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

The underlying weakness: Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended buffer.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • 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 Out-of-bounds Write vulnerabilities (CWE-787)

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 Out-of-bounds Write vulnerabilities

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