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CVE-2024-44934· NVD / CVE Program· CNA Linux

net: bridge: mcast: wait for previous gc cycles when removing port

In the Linux kernel, the following vulnerability has been resolved: net: bridge: mcast: wait for previous gc cycles when removing port syzbot hit a use-after-free[1] which is caused because the bridge doesn't make sure that all previous garbage has been collected when removing a port. What happens is: CPU 1 CPU 2 start gc cycle remove port acquire gc lock first wait for lock call br_multicasg_gc() directly acquire lock now but free port the port can be freed while grp timers still running Make sure all previous gc cycles have finished by using flush_work before freeing the port. [1] BUG: KASAN: slab-use-after-free in br_multicast_port_group_expired+0x4c0/0x550 net/bridge/br_multicast.c:861 Read of size 8 at addr ffff888071d6d000 by task syz.5.1232/9699 CPU: 1 PID: 9699 Comm: syz.5.1232 Not tainted 6.10.0-rc5-syzkaller-00021-g24ca36a562d6 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114 print_address_description mm/kasan/report.c:377 [inline] print_report+0xc3/0x620 mm/kasan/report.c:488 kasan_report+0xd9/0x110 mm/kasan/report.c:601 br_multicast_port_group_expired+0x4c0/0x550 net/bridge/br_multicast.c:861 call_timer_fn+0x1a3/0x610 kernel/time/timer.c:1792 expire_timers kernel/time/timer.c:1843 [inline] __run_timers+0x74b/0xaf0 kernel/time/timer.c:2417 __run_timer_base kernel/time/timer.c:2428 [inline] __run_timer_base kernel/time/timer.c:2421 [inline] run_timer_base+0x111/0x190 kernel/time/timer.c:2437

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Aug 26, 2024
Updated
Aug 5, 2026
EPSS
0.2% · 11th percentile
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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.

Affected systems

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 kernel5.10 and later · before 5.15.165
  • linux linux kernel5.16 and later · before 6.1.105
  • linux linux kernel6.2 and later · before 6.6.46
  • linux linux kernel6.7 and later · before 6.10.5
  • linux linux kernel6.11

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

    • 5.10affected
    • e12cec65b5546f19217e26aafb8add6e2fadca18 and later · before 1e16828020c674b3be85f52685e8b80f9008f50faffected · git
    • e12cec65b5546f19217e26aafb8add6e2fadca18 and later · before 0d8b26e10e680c01522d7cc14abe04c3265a928faffected · git
    • e12cec65b5546f19217e26aafb8add6e2fadca18 and later · before e3145ca904fa8dbfd1a5bf0187905bc117b0efceaffected · git
    • e12cec65b5546f19217e26aafb8add6e2fadca18 and later · before b2f794b168cf560682ff976b255aa6d29d14a658affected · git
    • e12cec65b5546f19217e26aafb8add6e2fadca18 and later · before 92c4ee25208d0f35dafc3213cdf355fbe449e078affected · git
    • before 5.10not affected · semver
    • 5.15.165 and later · up to and including 5.15.*not affected · semver
    • 6.1.105 and later · up to and including 6.1.*not affected · semver
    • 6.6.46 and later · up to and including 6.6.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.106-16.1.106-1
Debian:13linuxbefore 6.10.6-16.10.6-1
openSUSE:Leap 15.6dtb-aarch64before 6.4.0-150600.23.33.16.4.0-150600.23.33.1
openSUSE:Leap 15.6kernel-debugbefore 6.4.0-150600.23.33.16.4.0-150600.23.33.1
openSUSE:Leap 15.6kernel-kvmsmallbefore 6.4.0-150600.23.33.16.4.0-150600.23.33.1
openSUSE:Leap 15.6kernel-obs-qabefore 6.4.0-150600.23.33.16.4.0-150600.23.33.1
SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOSkernel-64kbbefore 5.14.21-150500.55.91.15.14.21-150500.55.91.1
SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOSkernel-docsbefore 5.14.21-150500.55.91.15.14.21-150500.55.91.1
SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOSkernel-obs-buildbefore 5.14.21-150500.55.91.15.14.21-150500.55.91.1
SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOSkernel-sourcebefore 5.14.21-150500.55.91.15.14.21-150500.55.91.1
SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOSkernel-symsbefore 5.14.21-150500.55.91.15.14.21-150500.55.91.1
SUSE:Linux Enterprise Live Patching 15 SP5kernel-livepatch-SLE15-SP5_Update_22before 1-150500.11.3.11-150500.11.3.1
SUSE:Linux Enterprise Live Patching 15 SP6kernel-livepatch-SLE15-SP6_Update_7before 1-150600.13.3.11-150600.13.3.1
SUSE:Linux Enterprise Live Patching 15 SP6kernel-livepatch-SLE15-SP6_Update_7before 1-150600.13.3.11-150600.13.3.1
SUSE:Linux Enterprise Live Patching 15 SP6kernel-livepatch-SLE15-SP6-RT_Update_7before 1-150600.1.3.11-150600.1.3.1
SUSE:Linux Enterprise Live Patching 15 SP6kernel-livepatch-SLE15-SP6-RT_Update_7before 1-150600.1.3.11-150600.1.3.1
SUSE:Linux Enterprise Micro 5.5kernel-defaultbefore 5.14.21-150500.55.91.15.14.21-150500.55.91.1
SUSE:Linux Enterprise Micro 5.5kernel-default-basebefore 5.14.21-150500.55.91.1.150500.6.41.15.14.21-150500.55.91.1.150500.6.41.1
SUSE:Linux Enterprise Micro 5.5kernel-rtbefore 5.14.21-150500.13.82.15.14.21-150500.13.82.1
SUSE:Linux Enterprise Micro 5.5kernel-source-rtbefore 5.14.21-150500.13.82.15.14.21-150500.13.82.1
SUSE:Linux Enterprise Module for Basesystem 15 SP6kernel-64kbbefore 6.4.0-150600.23.33.16.4.0-150600.23.33.1
SUSE:Linux Enterprise Module for Basesystem 15 SP6kernel-64kbbefore 6.4.0-150600.23.33.16.4.0-150600.23.33.1
SUSE:Linux Enterprise Module for Basesystem 15 SP6kernel-defaultbefore 6.4.0-150600.23.33.16.4.0-150600.23.33.1
SUSE:Linux Enterprise Module for Basesystem 15 SP6kernel-defaultbefore 6.4.0-150600.23.33.16.4.0-150600.23.33.1

+36

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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 Linux0d8b26e10e680c01522d7cc14abe04c3265a928fVendor (CNA)
Linux Linux1e16828020c674b3be85f52685e8b80f9008f50fVendor (CNA)
Linux Linux92c4ee25208d0f35dafc3213cdf355fbe449e078Vendor (CNA)
Linux Linuxb2f794b168cf560682ff976b255aa6d29d14a658Vendor (CNA)
Linux Linuxe3145ca904fa8dbfd1a5bf0187905bc117b0efceVendor (CNA)
debian:linux6.1.106-1 · Debian:12Package registry (OSV)
opensuse:kernel-azure6.4.0-150600.8.23.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-rt6.4.0-150600.10.23.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-source-azure6.4.0-150600.8.23.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-syms-azure6.4.0-150600.8.23.1 · openSUSE:Leap 15.6Package registry (OSV)
suse:kernel-azure6.4.0-150600.8.23.1 · SUSE:Linux Enterprise Module for Public Cloud 15 SP6Package registry (OSV)
suse:kernel-livepatch-SLE15-SP6-RT_Update_71-150600.1.3.1 · SUSE:Linux Enterprise Live Patching 15 SP6Package registry (OSV)
suse:kernel-rt6.4.0-150600.10.23.1 · SUSE:Real Time Module 15 SP6Package registry (OSV)
suse:kernel-rt_debug6.4.0-150600.10.23.1 · SUSE:Real Time Module 15 SP6Package registry (OSV)
suse:kernel-source-azure6.4.0-150600.8.23.1 · SUSE:Linux Enterprise Module for Public Cloud 15 SP6Package registry (OSV)
suse:kernel-source-rt6.4.0-150600.10.23.1 · SUSE:Real Time Module 15 SP6Package registry (OSV)
suse:kernel-syms-azure6.4.0-150600.8.23.1 · SUSE:Linux Enterprise Module for Public Cloud 15 SP6Package registry (OSV)
suse:kernel-syms-rt6.4.0-150600.10.23.1 · SUSE:Real Time Module 15 SP6Package 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

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.

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

  • 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-primary

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.

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.

Noroxi analysis

No Noroxi analysis for this record yet

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Change log

  1. Fix✗ → ✓

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References

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