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CVE-2018-15862· NVD / CVE Program· CNA mitre

Unchecked NULL pointer usage in LookupModMask in xkbcomp/expr.c in xkbcommon before 0.8.2 could be used by local attackers to crash (NULL po

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.43% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: libxkbcommon (Debian:12) 0.8.2-1; gdm (Red Hat:enterprise_linux:7::client) 1:3.28.2-16.el7; gdm-debuginfo (Red Hat:enterprise_linux:7::client) 1:3.28.2-16.el7.

Low priority for now. Upgrade to libxkbcommon (Debian:12) 0.8.2-1; gdm (Red Hat:enterprise_linux:7::client) 1:3.28.2-16.el7; gdm-debuginfo (Red Hat:enterprise_linux:7::client) 1:3.28.2-16.el7 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Unchecked NULL pointer usage in LookupModMask in xkbcomp/expr.c in xkbcommon before 0.8.2 could be used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file with invalid virtual modifiers.

MediumCVSS 5.5 · v3.0—No exploit Fix available
Published
Aug 25, 2018
Updated
Jun 16, 2026
EPSS
0.4% · 36th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
xkbcommonlibxkbcommon
xkbcommonxkbcommon
canonicalubuntu linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • canonical ubuntu linux14.04
  • canonical ubuntu linux16.04
  • canonical ubuntu linux18.04
  • xkbcommon libxkbcommonup to 0.8.1 inclusive
  • xkbcommon xkbcommonup to 0.8.1 inclusive

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12libxkbcommonbefore 0.8.2-10.8.2-1
Red Hat:enterprise_linux:7::clientgdmbefore 1:3.28.2-16.el71:3.28.2-16.el7
Red Hat:enterprise_linux:7::clientgdm-debuginfobefore 1:3.28.2-16.el71:3.28.2-16.el7
Red Hat:enterprise_linux:7::clientgdm-develbefore 1:3.28.2-16.el71:3.28.2-16.el7
Red Hat:enterprise_linux:7::clientgdm-pam-extensions-develbefore 1:3.28.2-16.el71:3.28.2-16.el7
Red Hat:enterprise_linux:7::clientlibX11before 0:1.6.7-2.el70:1.6.7-2.el7
Red Hat:enterprise_linux:7::clientlibX11-commonbefore 0:1.6.7-2.el70:1.6.7-2.el7
Red Hat:enterprise_linux:7::clientlibX11-debuginfobefore 0:1.6.7-2.el70:1.6.7-2.el7
Red Hat:enterprise_linux:7::clientlibX11-develbefore 0:1.6.7-2.el70:1.6.7-2.el7
Red Hat:enterprise_linux:7::clientlibxkbcommonbefore 0:0.7.1-3.el70:0.7.1-3.el7
Red Hat:enterprise_linux:7::clientlibxkbcommon-debuginfobefore 0:0.7.1-3.el70:0.7.1-3.el7
Red Hat:enterprise_linux:7::clientlibxkbcommon-develbefore 0:0.7.1-3.el70:0.7.1-3.el7
Red Hat:enterprise_linux:7::clientlibxkbcommon-x11before 0:0.7.1-3.el70:0.7.1-3.el7
Red Hat:enterprise_linux:7::clientlibxkbcommon-x11-develbefore 0:0.7.1-3.el70:0.7.1-3.el7
Red Hat:enterprise_linux:7::clientxorg-x11-drv-atibefore 0:19.0.1-2.el70:19.0.1-2.el7
Red Hat:enterprise_linux:7::clientxorg-x11-drv-ati-debuginfobefore 0:19.0.1-2.el70:19.0.1-2.el7
Red Hat:enterprise_linux:7::clientxorg-x11-drv-vesabefore 0:2.4.0-3.el70:2.4.0-3.el7
Red Hat:enterprise_linux:7::clientxorg-x11-drv-vesa-debuginfobefore 0:2.4.0-3.el70:2.4.0-3.el7
Red Hat:enterprise_linux:7::clientxorg-x11-drv-wacombefore 0:0.36.1-3.el70:0.36.1-3.el7
Red Hat:enterprise_linux:7::clientxorg-x11-drv-wacom-debuginfobefore 0:0.36.1-3.el70:0.36.1-3.el7
Red Hat:enterprise_linux:7::clientxorg-x11-drv-wacom-develbefore 0:0.36.1-3.el70:0.36.1-3.el7
Red Hat:enterprise_linux:7::clientxorg-x11-serverbefore 0:1.20.4-7.el70:1.20.4-7.el7
Red Hat:enterprise_linux:7::clientxorg-x11-server-commonbefore 0:1.20.4-7.el70:1.20.4-7.el7
Red Hat:enterprise_linux:7::clientxorg-x11-server-debuginfobefore 0:1.20.4-7.el70:1.20.4-7.el7

+13

Same product

xkbcommon: all records

Other highest-scoring records for the same primary product.

  • CVE-2018-15857An invalid free in ExprAppendMultiKeysymList in xkbcomp/ast-build.c in xkbcommon before 0.8.1 could be used by local attackers to crash xkbc
    31Monitor
  • CVE-2018-15864Unchecked NULL pointer usage in resolve_keysym in xkbcomp/parser.y in xkbcommon before 0.8.2 could be used by local attackers to crash (NULL
    22Monitor
  • CVE-2018-15863Unchecked NULL pointer usage in ResolveStateAndPredicate in xkbcomp/compat.c in xkbcommon before 0.8.2 could be used by local attackers to c
    22Monitor
  • CVE-2018-15861Unchecked NULL pointer usage in ExprResolveLhs in xkbcomp/expr.c in xkbcommon before 0.8.2 could be used by local attackers to crash (NULL p
    22Monitor
  • CVE-2018-15859Unchecked NULL pointer usage when parsing invalid atoms in ExprResolveLhs in xkbcomp/expr.c in xkbcommon before 0.8.2 could be used by local
    22Monitor
  • CVE-2018-15858Unchecked NULL pointer usage when handling invalid aliases in CopyKeyAliasesToKeymap in xkbcomp/keycodes.c in xkbcommon before 0.8.1 could b
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:libxkbcommon0.8.2-1 · Debian:12Package registry (OSV)
red hat:gdm1:3.28.2-16.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:gdm-debuginfo1:3.28.2-16.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:libX110:1.6.7-2.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:libX11-common0:1.6.7-2.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:libX11-debuginfo0:1.6.7-2.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:libX11-devel0:1.6.7-2.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:libxkbcommon0:0.7.1-3.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:libxkbcommon-debuginfo0:0.7.1-3.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:libxkbcommon-x110:0.7.1-3.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:xorg-x11-drv-ati0:19.0.1-2.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:xorg-x11-drv-ati-debuginfo0:19.0.1-2.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:xorg-x11-drv-vesa0:2.4.0-3.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
suse:libxkbcommon0.8.2-3.3.1 · SUSE:Linux Enterprise Module for Basesystem 15Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-476 · NULL Pointer Dereference

CVSS vector

CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records