CVE-2021-46990: powerpc/64s: Fix crashes when toggling entry flush barrier
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: 0.23% (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: Linux Linux 0b4eb172cc12dc102cd0ad013e53ee4463db9508, 0c25a7bb697f2e6ee65b6d63782f675bf129511a, 2db22ba4e0e103f00e0512e0ecce36ac78c644f8.
- Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).
Low priority for now. Upgrade to Linux Linux 0b4eb172cc12dc102cd0ad013e53ee4463db9508, 0c25a7bb697f2e6ee65b6d63782f675bf129511a, 2db22ba4e0e103f00e0512e0ecce36ac78c644f8 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
Primary sources: NVD · CVE.org · FIRST EPSS
In the Linux kernel, the following vulnerability has been resolved: powerpc/64s: Fix crashes when toggling entry flush barrier The entry flush mitigation can be enabled/disabled at runtime via a debugfs file (entry_flush), which causes the kernel to patch itself to enable/disable the relevant mitigations. However depending on which mitigation we're using, it may not be safe to do that patching while other CPUs are active. For example the following crash: sleeper[15639]: segfault (11) at c000000000004c20 nip c000000000004c20 lr c000000000004c20 Shows that we returned to userspace with a corrupted LR that points into the kernel, due to executing the partially patched call to the fallback entry flush (ie. we missed the LR restore). Fix it by doing the patching under stop machine. The CPUs that aren't doing the patching will be spinning in the core of the stop machine logic. That is currently sufficient for our purposes, because none of the patching we do is to that code or anywhere in the vicinity.
- Published
- Feb 28, 2024
- Updated
- Jun 17, 2026
- EPSS
- 0.2% · 14th percentile
- CWE
- —
Report tools
Action score
22
Monitor
Low priority for now.
- CVSS
- 22 / 40 · 5.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.2%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
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.
Is your version affected? Check itNoroxi 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.
We use this product, ask for helpAffected 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.
| Vendor | Product | CPE |
|---|---|---|
| linux | linux kernel | cpe:2.3:o:linux:linux_kernel |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- linux linux kernel4.4.245 and later · before 4.4.269
- linux linux kernel4.9.245 and later · before 4.9.269
- linux linux kernel4.14.208 and later · before 4.14.233
- linux linux kernel4.19.159 and later · before 4.19.191
- linux linux kernel5.4.79 and later · before 5.4.120
- linux linux kernel5.10 and later · before 5.10.38
- linux linux kernel5.11 and later · before 5.11.22
- linux linux kernel5.12 and later · before 5.12.5
- linux linux kernel5.13
Versions reported by the vendor
Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.
Linux Linux
- e590b36718d6e740b7b19514f710402a6499164c, 5.10affected
- 4a1e90af718d1489ffcecc8f52486c4f5dc0f7a6 and later · before 8382b15864e5014261b4f36c2aa89723612ee058affected · git
- fa4bf9f38184ed7ca4916eb64f8c767d1e279c1f and later · before 0c25a7bb697f2e6ee65b6d63782f675bf129511aaffected · git
- db01cad9efe3c3838a6b3a3f68affd295c4b92d6 and later · before ee4b7aab93c2631c3bb0753023c5dda592bb666baffected · git
- f69bb4e51f41973fb7594be1479fa689831efe1a and later · before 2db22ba4e0e103f00e0512e0ecce36ac78c644f8affected · git
- b65458b6be8032c5179d4f562038575d7b3a6be3 and later · before 0b4eb172cc12dc102cd0ad013e53ee4463db9508affected · git
- f79643787e0a0762d2409b7b8334e83f22d85695 and later · before d2e3590ca39ccfd8a5a46d8c7f095cb6c7b9ae92affected · git
- f79643787e0a0762d2409b7b8334e83f22d85695 and later · before dd0d6117052faace5440db20fc37175efe921c7daffected · git
- f79643787e0a0762d2409b7b8334e83f22d85695 and later · before 5bc00fdda1e934c557351a9c751a205293e68cbfaffected · git
- f79643787e0a0762d2409b7b8334e83f22d85695 and later · before aec86b052df6541cc97c5fca44e5934cbea4963baffected · git
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | linux | before 5.10.38-1 | 5.10.38-1 |
| SUSE:Linux Enterprise High Availability Extension 12 SP5 | kernel-default | before 4.12.14-122.216.1 | 4.12.14-122.216.1 |
| SUSE:Linux Enterprise Live Patching 12 SP5 | kgraft-patch-SLE12-SP5_Update_56 | before 1-8.3.1 | 1-8.3.1 |
| SUSE:Linux Enterprise Real Time 12 SP5 | kernel-rt | before 4.12.14-10.182.1 | 4.12.14-10.182.1 |
| SUSE:Linux Enterprise Real Time 12 SP5 | kernel-rt_debug | before 4.12.14-10.182.1 | 4.12.14-10.182.1 |
| SUSE:Linux Enterprise Real Time 12 SP5 | kernel-source-rt | before 4.12.14-10.182.1 | 4.12.14-10.182.1 |
| SUSE:Linux Enterprise Real Time 12 SP5 | kernel-syms-rt | before 4.12.14-10.182.1 | 4.12.14-10.182.1 |
| SUSE:Linux Enterprise Server 12 SP5 | kernel-azure | before 4.12.14-16.182.1 | 4.12.14-16.182.1 |
| SUSE:Linux Enterprise Server 12 SP5 | kernel-source | before 4.12.14-122.216.1 | 4.12.14-122.216.1 |
| SUSE:Linux Enterprise Server 12 SP5 | kernel-source-azure | before 4.12.14-16.182.1 | 4.12.14-16.182.1 |
| SUSE:Linux Enterprise Server 12 SP5 | kernel-syms | before 4.12.14-122.216.1 | 4.12.14-122.216.1 |
| SUSE:Linux Enterprise Server 12 SP5 | kernel-syms-azure | before 4.12.14-16.182.1 | 4.12.14-16.182.1 |
| SUSE:Linux Enterprise Software Development Kit 12 SP5 | kernel-docs | before 4.12.14-122.216.1 | 4.12.14-122.216.1 |
| SUSE:Linux Enterprise Software Development Kit 12 SP5 | kernel-obs-build | before 4.12.14-122.216.1 | 4.12.14-122.216.1 |
Same product
linux: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV90Now
- CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe…KEV89Now
- CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV85Now
Published before and after this one in the same product
- ← EarlierCVE-2021-46988Feb 28, 2024 · userfaultfd: release page in error path to avoid BUG_ON22Monitor
- ← EarlierCVE-2021-46989Feb 28, 2024 · hfsplus: prevent corruption in shrinking truncate28Monitor
- Later →CVE-2021-46991Feb 28, 2024 · i40e: Fix use-after-free in i40e_client_subtask()31Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Linux Linux | 0b4eb172cc12dc102cd0ad013e53ee4463db9508 | Vendor (CNA) |
| Linux Linux | 0c25a7bb697f2e6ee65b6d63782f675bf129511a | Vendor (CNA) |
| Linux Linux | 2db22ba4e0e103f00e0512e0ecce36ac78c644f8 | Vendor (CNA) |
| Linux Linux | 4.14.233 | Vendor (CNA) |
| Linux Linux | 4.19.191 | Vendor (CNA) |
| Linux Linux | 4.4.269 | Vendor (CNA) |
| Linux Linux | 4.9.269 | Vendor (CNA) |
| Linux Linux | 5.10 | Vendor (CNA) |
| Linux Linux | 5.4.120 | Vendor (CNA) |
| Linux Linux | 5bc00fdda1e934c557351a9c751a205293e68cbf | Vendor (CNA) |
| Linux Linux | 8382b15864e5014261b4f36c2aa89723612ee058 | Vendor (CNA) |
| Linux Linux | aec86b052df6541cc97c5fca44e5934cbea4963b | Vendor (CNA) |
| Linux Linux | d2e3590ca39ccfd8a5a46d8c7f095cb6c7b9ae92 | Vendor (CNA) |
| Linux Linux | dd0d6117052faace5440db20fc37175efe921c7d | Vendor (CNA) |
| Linux Linux | ee4b7aab93c2631c3bb0753023c5dda592bb666b | Vendor (CNA) |
| debian:linux | 5.10.38-1 · Debian:12 | Package registry (OSV) |
| suse:kernel-azure | 4.12.14-16.182.1 · SUSE:Linux Enterprise Server 12 SP5 | Package registry (OSV) |
| suse:kernel-default | 4.12.14-122.216.1 · SUSE:Linux Enterprise High Availability Extension 12 SP5 | Package registry (OSV) |
| suse:kernel-docs | 4.12.14-122.216.1 · SUSE:Linux Enterprise Software Development Kit 12 SP5 | Package registry (OSV) |
| suse:kernel-obs-build | 4.12.14-122.216.1 · SUSE:Linux Enterprise Software Development Kit 12 SP5 | Package registry (OSV) |
| suse:kernel-rt | 4.12.14-10.182.1 · SUSE:Linux Enterprise Real Time 12 SP5 | Package registry (OSV) |
| suse:kernel-rt_debug | 4.12.14-10.182.1 · SUSE:Linux Enterprise Real Time 12 SP5 | Package registry (OSV) |
| suse:kernel-source | 4.12.14-122.216.1 · SUSE:Linux Enterprise Server 12 SP5 | Package registry (OSV) |
| suse:kernel-source-azure | 4.12.14-16.182.1 · SUSE:Linux Enterprise Server 12 SP5 | Package registry (OSV) |
| suse:kernel-source-rt | 4.12.14-10.182.1 · SUSE:Linux Enterprise Real Time 12 SP5 | Package registry (OSV) |
| suse:kernel-syms-azure | 4.12.14-16.182.1 · SUSE:Linux Enterprise Server 12 SP5 | Package registry (OSV) |
| suse:kernel-syms-rt | 4.12.14-10.182.1 · SUSE:Linux Enterprise Real Time 12 SP5 | Package registry (OSV) |
| suse:kgraft-patch-SLE12-SP5_Update_56 | 1-8.3.1 · SUSE:Linux Enterprise Live Patching 12 SP5 | Package 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.
No history yet (it accumulates with the daily EPSS job).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, 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).
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-24-0145 · Feb 29, 2024(Linux Kernel Güncellemesi)
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)
—
CVSS vector
CVSS:3.1/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
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (8 more)Show less
- git.kernel.org/stable/c/0c25a7bb697f2e6ee65b6d63782f675bf129511a
- git.kernel.org/stable/c/2db22ba4e0e103f00e0512e0ecce36ac78c644f8
- git.kernel.org/stable/c/5bc00fdda1e934c557351a9c751a205293e68cbf
- git.kernel.org/stable/c/8382b15864e5014261b4f36c2aa89723612ee058
- git.kernel.org/stable/c/aec86b052df6541cc97c5fca44e5934cbea4963b
- git.kernel.org/stable/c/d2e3590ca39ccfd8a5a46d8c7f095cb6c7b9ae92
- git.kernel.org/stable/c/dd0d6117052faace5440db20fc37175efe921c7d
- git.kernel.org/stable/c/ee4b7aab93c2631c3bb0753023c5dda592bb666b
Vendor advisories and official records. Exploit/PoC links are deliberately left out.