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NVD / CVE Program· CNA Linux

CVE-2026-52947: net: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove

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: 0.10% (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 03bfa95e452e2b6ccd76a332060ae4feaf5ad84d, 2047c2aa0963bb2872fd722300a15bcb441a4c00, 2aa4c12723fe432e623462a3be42a197a128722b; azl3 kernel 6.6.141.1-1 on Azure Linux 3.0 6.6.143.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 03bfa95e452e2b6ccd76a332060ae4feaf5ad84d, 2047c2aa0963bb2872fd722300a15bcb441a4c00, 2aa4c12723fe432e623462a3be42a197a128722b; azl3 kernel 6.6.141.1-1 on Azure Linux 3.0 6.6.143.1-1 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: net: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove In qrtr_port_remove(), the socket reference count is decremented via __sock_put() before the port is removed from the qrtr_ports XArray and before the RCU grace period elapses. This breaks the fundamental RCU update paradigm. It exposes a race window where a concurrent RCU reader (such as qrtr_reset_ports() or qrtr_port_lookup()) can obtain a pointer to the socket from the XArray, and attempt to call sock_hold() on a socket whose reference count has already dropped to zero. This exact race condition was hit during syzkaller fuzzing, leading to the following refcount saturation warning and a potential Use-After-Free: refcount_t: saturated; leaking memory. WARNING: CPU: 3 PID: 1273 at lib/refcount.c:22 refcount_warn_saturate+0xae/0x1d0 Modules linked in: qrtr(+) bochs drm_shmem_helper ... Call Trace: <TASK> qrtr_reset_ports net/qrtr/af_qrtr.c:768 [inline] [qrtr] __qrtr_bind.isra.0+0x48b/0x570 net/qrtr/af_qrtr.c:805 [qrtr] qrtr_bind+0x17d/0x210 net/qrtr/af_qrtr.c:901 [qrtr] kernel_bind+0xe4/0x120 net/socket.c:3592 qrtr_ns_init+0x1a6/0x380 net/qrtr/ns.c:715 [qrtr] qrtr_proto_init+0x3b/0xff0 net/qrtr/af_qrtr.c:169 [qrtr] do_one_initcall+0xf5/0x5e0 init/main.c:1283 ... </TASK> Fix this by deferring the reference count decrement until after the xa_erase() and the synchronize_rcu() complete. (Note: The v1 of this patch incorrectly replaced __sock_put() with sock_put(). As Simon Horman pointed out, the callers of qrtr_port_remove() still hold a reference to the socket, so freeing the socket memory here would lead to a subsequent UAF in the caller. Thus, the __sock_put() is kept, but only repositioned to close the RCU race.)

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Jun 24, 2026
Updated
Oct 19, 2026
EPSS
0.1% · 1th 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 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.8
NVD has not scored this yet; the score shown is the CNA’s.

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

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  • A fix has been released

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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 kernel4.7 and later · before 5.10.259
  • linux linux kernel5.11 and later · before 5.15.210
  • linux linux kernel5.16 and later · before 6.1.176
  • linux linux kernel6.2 and later · before 6.6.143
  • linux linux kernel6.7 and later · before 6.12.94
  • linux linux kernel6.13 and later · before 6.18.36
  • linux linux kernel6.19 and later · before 7.0.13
  • linux linux kernel7.1

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

    • 4.7affected
    • bdabad3e363d825ddf9679dd431cca0b2c30f881 and later · before 2aa4c12723fe432e623462a3be42a197a128722baffected · git
    • bdabad3e363d825ddf9679dd431cca0b2c30f881 and later · before 03bfa95e452e2b6ccd76a332060ae4feaf5ad84daffected · git
    • bdabad3e363d825ddf9679dd431cca0b2c30f881 and later · before 474293d90880622fde9d2430fb0165767090f7b3affected · git
    • bdabad3e363d825ddf9679dd431cca0b2c30f881 and later · before 2047c2aa0963bb2872fd722300a15bcb441a4c00affected · git
    • bdabad3e363d825ddf9679dd431cca0b2c30f881 and later · before 7de2d447072be3b1a76793f034432338fc9c494baffected · git
    • bdabad3e363d825ddf9679dd431cca0b2c30f881 and later · before ab269990ed58143a92a263be1bee626d82ac03daaffected · git
    • bdabad3e363d825ddf9679dd431cca0b2c30f881 and later · before 3b20ec8f31e8a6a6782243f473b0abd3463621dfaffected · git
    • bdabad3e363d825ddf9679dd431cca0b2c30f881 and later · before a2171131ecda1ed61a594a1eb715e75fdad0fef5affected · git
    • before 4.7not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:10kernelbefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-64kbefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-64k-corebefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-64k-debugbefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-64k-debug-corebefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-64k-debug-develbefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-64k-debug-devel-matchedbefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-64k-debug-modulesbefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-corebefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-extrabefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-64k-develbefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-64k-devel-matchedbefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-64k-modulesbefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-64k-modules-corebefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-64k-modules-extrabefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-corebefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-cross-headersbefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-debugbefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-debug-corebefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-debug-develbefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-debug-devel-matchedbefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-debug-modulesbefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2
AlmaLinux:10kernel-debug-modules-corebefore 6.12.0-211.53.1.el10_26.12.0-211.53.1.el10_2

+96

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-2026-52945Jun 24, 2026 · Revert "wireguard: device: enable threaded NAPI"
    30Monitor
  • ← EarlierCVE-2026-52946Jun 24, 2026 · fs/fcntl: fix SOFTIRQ-unsafe lock order in fasync signaling
    30Monitor
  • Later →CVE-2026-52948Jun 24, 2026 · i2c: dev: prevent integer overflow in I2C_TIMEOUT ioctl
    22Monitor

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 Linux03bfa95e452e2b6ccd76a332060ae4feaf5ad84dVendor (CNA)
Linux Linux2047c2aa0963bb2872fd722300a15bcb441a4c00Vendor (CNA)
Linux Linux2aa4c12723fe432e623462a3be42a197a128722bVendor (CNA)
Linux Linux3b20ec8f31e8a6a6782243f473b0abd3463621dfVendor (CNA)
Linux Linux474293d90880622fde9d2430fb0165767090f7b3Vendor (CNA)
Linux Linux7de2d447072be3b1a76793f034432338fc9c494bVendor (CNA)
Linux Linuxa2171131ecda1ed61a594a1eb715e75fdad0fef5Vendor (CNA)
Linux Linuxab269990ed58143a92a263be1bee626d82ac03daVendor (CNA)
azl3 kernel 6.6.141.1-1 on Azure Linux 3.06.6.143.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
almalinux:kernel6.12.0-211.53.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k6.12.0-211.53.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-core6.12.0-211.53.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug6.12.0-211.53.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-core6.12.0-211.53.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel6.12.0-211.53.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched6.12.0-211.53.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules6.12.0-211.53.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-core6.12.0-211.53.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra6.12.0-211.53.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel6.12.0-211.53.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel-matched6.12.0-211.53.1.el10_2 · AlmaLinux:10Package registry (OSV)
debian:linux6.1.176-1 · Debian:12Package registry (OSV)
red hat:kernel-64k-debug-debuginfo0:6.12.0-211.53.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debug-devel0:6.12.0-211.53.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debug-devel-matched0:6.12.0-211.53.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debuginfo0:6.12.0-211.53.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-devel0:6.12.0-211.53.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-devel-matched0:6.12.0-211.53.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debug-debuginfo0:6.12.0-211.53.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debug-devel0:6.12.0-211.53.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)

+6

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.

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.

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-416 · Use After Free

CVSS vector

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

nvd-secondary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

c
free(dev->buf);/* ... another thread is still running ... */process(dev->buf);

Fixed

c
lock(&dev->lock);free(dev->buf);dev->buf = NULL;unlock(&dev->lock);

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

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

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

References

Show all references (8 more)

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

All records