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NVD / CVE Program· CNA Linux

CVE-2026-72323: ipv4: igmp: Fix potential UAF in igmp_gq_start_timer()

CriticalCVSS 9.8 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 39/100)

  • 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: 0.72% (FIRST EPSS); higher than 54.5% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: Linux Linux 165258303357e54b75fc19b341ae2a2b7c9e3910, 40a1e998cb266ed4cb529a0bb4fee2b0ba732702, 7265c747eec415ca3109a6a14a419f7ae433b780.

Low priority for now. Upgrade to Linux Linux 165258303357e54b75fc19b341ae2a2b7c9e3910, 40a1e998cb266ed4cb529a0bb4fee2b0ba732702, 7265c747eec415ca3109a6a14a419f7ae433b780 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: ipv4: igmp: Fix potential UAF in igmp_gq_start_timer() A race condition exists between device teardown (inetdev_destroy) and incoming IGMP query processing (igmp_rcv), leading to a Use-After-Free in the IGMP timer callback. During device destruction, inetdev_destroy() drops the primary reference to in_device, which can drop its refcount to 0. The actual freeing of in_device memory is deferred via RCU (using call_rcu()). Concurrently, igmp_rcv() runs under RCU read lock and obtains the in_device pointer. Because the memory is RCU-protected, CPU-0 can safely dereference in_device even if its refcount has hit 0. However, if CPU-0 calls igmp_gq_start_timer() and re-arms the timer, it attempts to acquire a reference using in_dev_hold(). This increments the refcount from 0 to 1, triggering a "refcount_t: addition on 0" warning. Since the in_device memory is still scheduled to be freed after the RCU grace period (as the free callback does not check the refcount again), the device is freed while the timer is still armed. When the timer expires, it accesses the freed memory, causing a kernel panic. Fix this by using refcount_inc_not_zero() (via a new helper in_dev_hold_safe()) to prevent acquiring a reference if the device is already being destroyed. If the refcount is 0, we do not arm the timer. A similar issue in IPv6 MLD is fixed in a subsequent patch.

Published
Aug 15, 2026
Updated
Oct 16, 2026
EPSS
0.7% · 54th percentile
CWE
—

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.7%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
9.8
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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  • 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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Noroxi analysis

What does it mean in your environment?

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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.

—

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

    • 2.6.12affected
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 7265c747eec415ca3109a6a14a419f7ae433b780affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before d107b4c4f8274763b7ea5ab05d45cef78e4b81baaffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 74b301f7f197517016befb5f5dfab01f7bc64be5affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 40a1e998cb266ed4cb529a0bb4fee2b0ba732702affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 165258303357e54b75fc19b341ae2a2b7c9e3910affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 75e984fe0cb9e7fbde0c8ee838c61ce8573d3ea3affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 8d4394ffa40508e0de72f464af351f6ca6a6cdc3affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 7b19c0f81ed1fdaec6bc522569be367199a9edf3affected · git
    • before 2.6.12not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.187-16.1.187-1
Debian:13linuxbefore 6.12.100-16.12.100-1
Debian:14linuxbefore 7.1.5-17.1.5-1
SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME COREkernel-defaultbefore 3.0.101-108.223.13.0.101-108.223.1
SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME COREkernel-docsbefore 3.0.101-108.223.13.0.101-108.223.1
SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME COREkernel-ec2before 3.0.101-108.223.13.0.101-108.223.1
SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME COREkernel-sourcebefore 3.0.101-108.223.13.0.101-108.223.1
SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME COREkernel-symsbefore 3.0.101-108.223.13.0.101-108.223.1
SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME COREkernel-tracebefore 3.0.101-108.223.13.0.101-108.223.1
SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME COREkernel-xenbefore 3.0.101-108.223.13.0.101-108.223.1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-72321Aug 15, 2026 · ipv4: igmp: Fix potential memory leaks in igmp_mod_timer() and igmp_stop_timer()
    0Monitor
  • ← EarlierCVE-2026-72322Aug 15, 2026 · ipv6: mcast: Fix potential UAF in MLD delayed work
    39Monitor
  • Later →CVE-2026-72324Aug 15, 2026 · gpio: mvebu: free generic chips on unbind
    0Monitor

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 Linux165258303357e54b75fc19b341ae2a2b7c9e3910Vendor (CNA)
Linux Linux40a1e998cb266ed4cb529a0bb4fee2b0ba732702Vendor (CNA)
Linux Linux7265c747eec415ca3109a6a14a419f7ae433b780Vendor (CNA)
Linux Linux74b301f7f197517016befb5f5dfab01f7bc64be5Vendor (CNA)
Linux Linux75e984fe0cb9e7fbde0c8ee838c61ce8573d3ea3Vendor (CNA)
Linux Linux7b19c0f81ed1fdaec6bc522569be367199a9edf3Vendor (CNA)
Linux Linux8d4394ffa40508e0de72f464af351f6ca6a6cdc3Vendor (CNA)
Linux Linuxd107b4c4f8274763b7ea5ab05d45cef78e4b81baVendor (CNA)
debian:linux6.1.187-1 · Debian:12Package registry (OSV)
suse:kernel-default3.0.101-108.223.1 · SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME COREPackage registry (OSV)
suse:kernel-docs3.0.101-108.223.1 · SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME COREPackage registry (OSV)
suse:kernel-ec23.0.101-108.223.1 · SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME COREPackage registry (OSV)
suse:kernel-source3.0.101-108.223.1 · SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME COREPackage registry (OSV)
suse:kernel-syms3.0.101-108.223.1 · SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME COREPackage registry (OSV)
suse:kernel-trace3.0.101-108.223.1 · SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME COREPackage registry (OSV)
suse:kernel-xen3.0.101-108.223.1 · SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME COREPackage 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.

EPSS, last 120 days+1% in 7 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • 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
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

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

nvd-secondary

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 (7 more)

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

All records