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CVE-2021-4188

NULL Pointer Dereference in mruby/mruby

6.8 MediumFix available

mruby is vulnerable to NULL Pointer Dereference

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
Low
Availability
High

Exploit likelihood

0.88%Up 0.3 points since Dec 30, 2021
90%50%10%1%

What each source reports

CVE List Score used 6.8

NULL Pointer Dereference in mruby/mruby

mruby is vulnerable to NULL Pointer Dereference

Record
CVE-2021-4188
CVSS 3.0
6.8 MediumCVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Weakness
CWE-476
Updated
2026-11-02
EUVDEUVD-2021-34048 6.8

mruby is vulnerable to NULL Pointer Dereference

Record
EUVD-2021-34048
CVSS 3.0
6.8 MediumCVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Updated
2026-11-03
GitHub AdvisoriesGHSA-wc43-284g-pqr5 No score

mruby is vulnerable to NULL Pointer Dereference

mruby is vulnerable to NULL Pointer Dereference

Record
GHSA-wc43-284g-pqr5
Weakness
CWE-476
Updated
2026-11-02
NVD 7.5

mruby is vulnerable to NULL Pointer Dereference

Record
CVE-2021-4188
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 3.0
6.8 MediumCVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness
CWE-476
Updated
2026-11-02
OSVALPINE-CVE-2021-4188 7.5

mruby is vulnerable to NULL Pointer Dereference

Record
ALPINE-CVE-2021-4188
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-03
OSV 7.5

mruby is vulnerable to NULL Pointer Dereference

Record
CVE-2021-4188
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2021-4188 7.5

mruby is vulnerable to NULL Pointer Dereference

Record
UBUNTU-CVE-2021-4188
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 3.0
6.8 MediumCVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
mruby
Alpine:v3.17
 before 3.1.0-r0
3.1.0-r0
mruby
Alpine:v3.18
 before 3.1.0-r0
3.1.0-r0
mruby
Alpine:v3.19
 before 3.1.0-r0
3.1.0-r0
mruby
Alpine:v3.20
 before 3.1.0-r0
3.1.0-r0
mruby
Alpine:v3.21
 before 3.1.0-r0
3.1.0-r0
mruby
Alpine:v3.22
 before 3.1.0-r0
3.1.0-r0
mruby
Alpine:v3.23
 before 3.1.0-r0
3.1.0-r0
mruby
Alpine:v3.24
 before 3.1.0-r0
3.1.0-r0
mruby
Ubuntu:16.04:LTS
 All versions, plus listed versions
1.1.0+20150817+gita1731254-11.1.0+20150906+git1cbbb7e1-11.2.0+20160315+git4f20d58a-1
 None known
mruby
Ubuntu:18.04:LTS
 All versions, plus listed versions
1.3.0-11.3.0+20170925+git38185028-11.3.0+20171029+git77edafb0-11.4.0-1
 None known
Show 6 moreShow less
Affected packages
PackageAffectedFixed
mruby
Ubuntu:20.04:LTS
 All versions, plus listed versions
2.0.0-1
 None known
mruby
Ubuntu:22.04:LTS
 All versions, plus listed versions
2.1.2-33.0.0-13.0.0-3
 None known
mruby
Ubuntu:24.04:LTS
 All versions, plus listed versions
3.2.0-13.2.0-2
 None known
mruby
Ubuntu:25.10
 All versions, plus listed versions
3.3.0-1
 None known
mruby
Ubuntu:26.10
 All versions, plus listed versions
3.4.0-23.4.0-34.0.0-1
 None known
mruby
Ubuntu:26.04:LTS
 All versions, plus listed versions
3.3.0-13.4.0-2
 None known

History

History
RecordedChangedSources
affected, aliases, facts, referencesOSV
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-4188 is a medium vulnerability (CVSS 6.8) in Mruby, published December 30, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.88%, the 59th percentile. Fixed in mruby 3.1.0-r0.

References

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