kernel: gss_mech_free in net/sunrpc/auth_gss/gss_mech_switch.c in the rpcsec_gss_krb5 implementation lacks certain domain_release calls, leading to a memory leak.
Published May 5, 2020
5.5
MEDIUMCVSS 3.1
EPSS 0.33%
Description
gss_mech_free in net/sunrpc/auth_gss/gss_mech_switch.c in the rpcsec_gss_krb5 implementation in the Linux kernel through 5.6.10 lacks certain domain_release calls, leading to a memory leak. Note: This was disputed with the assertion that the issue does not grant any access not already available. It is a problem that on unloading a specific kernel module some memory is leaked, but loading kernel modules is a privileged operation. A user could also write a kernel module to consume any amount of memory they like and load that replicating the effect of this bug
Affected products
No data.
Configuration 1
- ≤ 5.6.10
Configuration 2
- 14.04
- 16.04
- 18.04
- 20.04
No data.
Red Hat Enterprise Linux 5
kernel
Out of support scope
Red Hat Enterprise Linux 6
kernel
Out of support scope
Red Hat Enterprise Linux 7
kernel
Fix deferred
Red Hat Enterprise Linux 7
kernel-alt
Fix deferred
Red Hat Enterprise Linux 7
kernel-rt
Fix deferred
Red Hat Enterprise Linux 8
kernel
Affected
Red Hat Enterprise Linux 8
kernel-rt
Affected
Red Hat Enterprise MRG 2
kernel-rt
Out of support scope
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 5 | kernel | Out of support scope | n/a |
| Red Hat Enterprise Linux 6 | kernel | Out of support scope | n/a |
| Red Hat Enterprise Linux 7 | kernel | Fix deferred | n/a |
| Red Hat Enterprise Linux 7 | kernel-alt | Fix deferred | n/a |
| Red Hat Enterprise Linux 7 | kernel-rt | Fix deferred | n/a |
| Red Hat Enterprise Linux 8 | kernel | Affected | n/a |
| Red Hat Enterprise Linux 8 | kernel-rt | Affected | n/a |
| Red Hat Enterprise MRG 2 | kernel-rt | Out of support scope | n/a |
No package ranges for this CVE.
Remediation
Red Hat statement
This issue is rated as having Low impact because of the preconditions needed to trigger the issue (privileges requried to mount/unmount a module). The issue is also being disputed with MITRE (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-12656) as being a non-issue because of the privileges required.
Red Hat mitigation
There is no mitigation to this flaw other than to prevent the loading of the affected kernel module. A user with permission to load a kernel module would also likely have permission to overcome any blacklisting on the system.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
1 other source (Red Hat) ▾
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
No CVSS v3.0 score for this CVE.
AV:L/AC:L/Au:N/C:N/I:N/A:P
This CVE is not in the KEV list.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
NoneAutomatable
NoTechnical Impact
PartialDecision
n/aAssessed May 1, 2024 · SSVC 2.0.3
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 4, 2026.
Score over time
2021-2026- EPSS v1
- EPSS v5
- EPSS v2
- EPSS v3
- EPSS v4
Percentile over time
- EPSS v1
- EPSS v5
- EPSS v2
- EPSS v3
- EPSS v4
Table of values (12 key points)
Flat stretches are collapsed. Showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 4, 2026 | 0.33% (0.00334) | 24.46th | v5 (v2026.06.15) |
| Jun 15, 2026 | 0.33% (0.00334) | 24.97th | v5 (v2026.06.15) |
| Mar 17, 2025 | 0.13% (0.00131) | 30.20th | v4 (v2025.03.14) |
| Dec 12, 2024 | 0.04% (0.00045) | 16.02th | v3 (v2023.03.01) |
| Jun 10, 2024 | 0.04% (0.00045) | 14.07th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.04% (0.00045) | 12.06th | v3 (v2023.03.01) |
| Mar 6, 2023 | 0.95% (0.00950) | 32.28th | v2 (v2022.01.01) |
| Feb 4, 2022 | 1.67% (0.01669) | 53.27th | v2 (v2022.01.01) |
| Feb 3, 2022 | 5.36% (0.05363) | 79.74th | v1 |
| Jan 6, 2022 | 5.36% (0.05363) | 79.54th | v1 |
| Jan 5, 2022 | 1.25% (0.01247) | 69.74th | v5 (v2026.06.15) |
| Apr 14, 2021 | 1.25% (0.01247) | 0.00th | v1 |
References (9)
- http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00022.html vendor-advisoryx_refsource_SUSEMailing ListThird Party Advisory
- http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00008.html vendor-advisoryx_refsource_SUSEMailing ListThird Party Advisory
- https://access.redhat.com/security/cve/CVE-2020-12656 Vendor Advisory
- https://bugzilla.kernel.org/show_bug.cgi?id=206651 x_refsource_MISCIssue TrackingVendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1832860 Issue Tracking
- https://nvd.nist.gov/vuln/detail/CVE-2020-12656
- https://usn.ubuntu.com/4483-1/ vendor-advisoryx_refsource_UBUNTUThird Party Advisory
- https://usn.ubuntu.com/4485-1/ vendor-advisoryx_refsource_UBUNTUThird Party Advisory
- https://www.cve.org/CVERecord?id=CVE-2020-12656
| Link | Providers | Tags |
|---|---|---|
| http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00022.html | vendor-advisoryx_refsource_SUSEMailing ListThird Party Advisory | |
| http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00008.html | vendor-advisoryx_refsource_SUSEMailing ListThird Party Advisory | |
| https://access.redhat.com/security/cve/CVE-2020-12656 | Vendor Advisory | |
| https://bugzilla.kernel.org/show_bug.cgi?id=206651 | x_refsource_MISCIssue TrackingVendor Advisory | |
| https://bugzilla.redhat.com/show_bug.cgi?id=1832860 | Issue Tracking | |
| https://nvd.nist.gov/vuln/detail/CVE-2020-12656 | ||
| https://usn.ubuntu.com/4483-1/ | vendor-advisoryx_refsource_UBUNTUThird Party Advisory | |
| https://usn.ubuntu.com/4485-1/ | vendor-advisoryx_refsource_UBUNTUThird Party Advisory | |
| https://www.cve.org/CVERecord?id=CVE-2020-12656 |
Change history (0)
No recorded changes yet.