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NVD / CVE Program· CNA Linux

CVE-2021-47261: IB/mlx5: Fix initializing CQ fragments buffer

Noroxi assessment

Priority: Monitor (action score 31/100)

  • 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 1ec2dcd680c71d0d36fa25638b327a468babd5c9, 2ba0aa2feebda680ecfc3c552e867cf4d1b05a3a, 3e670c54eda238cb8a1ea93538a79ae89285c1c4.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 1ec2dcd680c71d0d36fa25638b327a468babd5c9, 2ba0aa2feebda680ecfc3c552e867cf4d1b05a3a, 3e670c54eda238cb8a1ea93538a79ae89285c1c4 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: IB/mlx5: Fix initializing CQ fragments buffer The function init_cq_frag_buf() can be called to initialize the current CQ fragments buffer cq->buf, or the temporary cq->resize_buf that is filled during CQ resize operation. However, the offending commit started to use function get_cqe() for getting the CQEs, the issue with this change is that get_cqe() always returns CQEs from cq->buf, which leads us to initialize the wrong buffer, and in case of enlarging the CQ we try to access elements beyond the size of the current cq->buf and eventually hit a kernel panic. [exception RIP: init_cq_frag_buf+103] [ffff9f799ddcbcd8] mlx5_ib_resize_cq at ffffffffc0835d60 [mlx5_ib] [ffff9f799ddcbdb0] ib_resize_cq at ffffffffc05270df [ib_core] [ffff9f799ddcbdc0] llt_rdma_setup_qp at ffffffffc0a6a712 [llt] [ffff9f799ddcbe10] llt_rdma_cc_event_action at ffffffffc0a6b411 [llt] [ffff9f799ddcbe98] llt_rdma_client_conn_thread at ffffffffc0a6bb75 [llt] [ffff9f799ddcbec8] kthread at ffffffffa66c5da1 [ffff9f799ddcbf50] ret_from_fork_nospec_begin at ffffffffa6d95ddd Fix it by getting the needed CQE by calling mlx5_frag_buf_get_wqe() that takes the correct source buffer as a parameter.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
May 21, 2024
Updated
Aug 5, 2026
EPSS
0.2% · 14th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 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.

CNA vs NVD score

NVD
7.8
CNA · Linux
7.8
agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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

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When you'll hear from us

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  • when exploit code appears or is weaponized
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  • 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
linuxlinux kernel

Affected versions

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

  • linux linux kernel4.17 and later · before 4.19.195
  • linux linux kernel4.20 and later · before 5.4.126
  • linux linux kernel5.5 and later · before 5.10.44
  • linux linux kernel5.11 and later · before 5.12.11
  • 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

    • 4.17affected
    • 388ca8be00370db132464e27f745b8a0add19fcb and later · before 1ec2dcd680c71d0d36fa25638b327a468babd5c9affected · git
    • 388ca8be00370db132464e27f745b8a0add19fcb and later · before e3ecd9c09fcc10cf6b2bc67e2990c397c40a8c26affected · git
    • 388ca8be00370db132464e27f745b8a0add19fcb and later · before 91f7fdc4cc10542ca1045c06aad23365f0d067e0affected · git
    • 388ca8be00370db132464e27f745b8a0add19fcb and later · before 3e670c54eda238cb8a1ea93538a79ae89285c1c4affected · git
    • 388ca8be00370db132464e27f745b8a0add19fcb and later · before 2ba0aa2feebda680ecfc3c552e867cf4d1b05a3aaffected · git
    • before 4.17not affected · semver
    • 4.19.195 and later · up to and including 4.19.*not affected · semver
    • 5.4.126 and later · up to and including 5.4.*not affected · semver
    • 5.10.44 and later · up to and including 5.10.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 5.10.46-15.10.46-1
SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSSkernel-default-basebefore 5.3.18-150200.24.194.1.150200.9.99.15.3.18-150200.24.194.1.150200.9.99.1
SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSSkernel-docsbefore 5.3.18-150200.24.194.15.3.18-150200.24.194.1
SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSSkernel-obs-buildbefore 5.3.18-150200.24.194.15.3.18-150200.24.194.1
SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSSkernel-preemptbefore 5.3.18-150200.24.194.15.3.18-150200.24.194.1
SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSSkernel-sourcebefore 5.3.18-150200.24.194.15.3.18-150200.24.194.1
SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSSkernel-symsbefore 5.3.18-150200.24.194.15.3.18-150200.24.194.1
SUSE:Linux Enterprise Live Patching 15 SP2kernel-defaultbefore 5.3.18-150200.24.194.15.3.18-150200.24.194.1
SUSE:Linux Enterprise Live Patching 15 SP2kernel-livepatch-SLE15-SP2_Update_49before 1-150200.5.3.11-150200.5.3.1
SUSE:Linux Enterprise Live Patching 15 SP3kernel-livepatch-SLE15-SP3_Update_41before 18-150300.2.118-150300.2.1
SUSE:Linux Enterprise Live Patching 15 SP3kernel-livepatch-SLE15-SP3_Update_42before 15-150300.2.115-150300.2.1
SUSE:Linux Enterprise Live Patching 15 SP3kernel-livepatch-SLE15-SP3_Update_44before 13-150300.2.113-150300.2.1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • 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 KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2021-47259May 21, 2024 · NFS: Fix use-after-free in nfs4_init_client()
    31Monitor
  • ← EarlierCVE-2021-47260May 21, 2024 · NFS: Fix a potential NULL dereference in nfs_get_client()
    22Monitor
  • Later →CVE-2021-47262May 21, 2024 · KVM: x86: Ensure liveliness of nested VM-Enter fail tracepoint message
    28Monitor

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
Linux Linux1ec2dcd680c71d0d36fa25638b327a468babd5c9Vendor (CNA)
Linux Linux2ba0aa2feebda680ecfc3c552e867cf4d1b05a3aVendor (CNA)
Linux Linux3e670c54eda238cb8a1ea93538a79ae89285c1c4Vendor (CNA)
Linux Linux91f7fdc4cc10542ca1045c06aad23365f0d067e0Vendor (CNA)
Linux Linuxe3ecd9c09fcc10cf6b2bc67e2990c397c40a8c26Vendor (CNA)
debian:linux5.10.46-1 · Debian:12Package registry (OSV)
suse:kernel-default5.3.18-150200.24.194.1 · SUSE:Linux Enterprise Live Patching 15 SP2Package registry (OSV)
suse:kernel-default-base5.3.18-150200.24.194.1.150200.9.99.1 · SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSSPackage registry (OSV)
suse:kernel-docs5.3.18-150200.24.194.1 · SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSSPackage registry (OSV)
suse:kernel-livepatch-SLE15-SP2_Update_491-150200.5.3.1 · SUSE:Linux Enterprise Live Patching 15 SP2Package registry (OSV)
suse:kernel-livepatch-SLE15-SP3_Update_4118-150300.2.1 · SUSE:Linux Enterprise Live Patching 15 SP3Package registry (OSV)
suse:kernel-livepatch-SLE15-SP3_Update_4215-150300.2.1 · SUSE:Linux Enterprise Live Patching 15 SP3Package registry (OSV)
suse:kernel-livepatch-SLE15-SP3_Update_4413-150300.2.1 · SUSE:Linux Enterprise Live Patching 15 SP3Package registry (OSV)
suse:kernel-obs-build5.3.18-150200.24.194.1 · SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSSPackage registry (OSV)
suse:kernel-preempt5.3.18-150200.24.194.1 · SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSSPackage registry (OSV)
suse:kernel-source5.3.18-150200.24.194.1 · SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSSPackage registry (OSV)
suse:kernel-syms5.3.18-150200.24.194.1 · SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSSPackage 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 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.

  • CVE-2021-472760 days apartftrace: Do not blindly read the ip address in ftrace_bug()
    22Monitor

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.

All national notices →

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

Weakness class (CWE)

CWE-706 · Use of Incorrectly-Resolved Name or Reference

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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.

Change log

  1. Fix✗ → ✓

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

References

Show all references (4 more)

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

All records