How severe is CVE-2018-15856?

CVE-2018-15856 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2018-15856 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (34th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-15856?

CVE-2018-15856 primarily affects Xkbcommon. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-15856?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2018-15856 published?

CVE-2018-15856 was published on 2018-08-25 and last updated on 2026-06-17.

CVE-2018-15856

CVE-2018-15856 is a medium-severity vulnerability in Xkbcommon with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-835.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
CVSS v2: 2.1
EPSS exploit prediction: 0% (34th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-835
Affected product: Xkbcommon
Published: 2018-08-25
Last modified: 2026-06-17

Description

An infinite loop when reaching EOL unexpectedly in compose/parser.c (aka the keymap parser) in xkbcommon before 0.8.1 could be used by local attackers to cause a denial of service during parsing of crafted keymap files.

Frequently asked questions

What is CVE-2018-15856?: An infinite loop when reaching EOL unexpectedly in compose/parser.c (aka the keymap parser) in xkbcommon before 0.8.1 could be used by local attackers to cause a denial of service during parsing of crafted keymap files.
How severe is CVE-2018-15856?: CVE-2018-15856 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2018-15856 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (34th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-15856?: CVE-2018-15856 primarily affects Xkbcommon. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-15856?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2018-15856 published?: CVE-2018-15856 was published on 2018-08-25 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:a:xkbcommon:xkbcommon:*:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*

More vulnerabilities in Xkbcommon

CVE-2018-15857 — High (CVSS 7.8): An invalid free in ExprAppendMultiKeysymList in xkbcomp/ast-build.c in xkbcommon before 0.8.1 could be used by local…
CVE-2018-15864 — Medium (CVSS 5.5): Unchecked NULL pointer usage in resolve_keysym in xkbcomp/parser.y in xkbcommon before 0.8.2 could be used by local…
CVE-2018-15863 — Medium (CVSS 5.5): Unchecked NULL pointer usage in ResolveStateAndPredicate in xkbcomp/compat.c in xkbcommon before 0.8.2 could be used by…
CVE-2018-15862 — Medium (CVSS 5.5): Unchecked NULL pointer usage in LookupModMask in xkbcomp/expr.c in xkbcommon before 0.8.2 could be used by local…
CVE-2018-15861 — Medium (CVSS 5.5): Unchecked NULL pointer usage in ExprResolveLhs in xkbcomp/expr.c in xkbcommon before 0.8.2 could be used by local…
CVE-2018-15859 — Medium (CVSS 5.5): Unchecked NULL pointer usage when parsing invalid atoms in ExprResolveLhs in xkbcomp/expr.c in xkbcommon before 0.8.2…

All CVEs affecting Xkbcommon →

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