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CVE Record

CVE-2024-44934: 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

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2024-44934 is a Linux kernel flaw in bridge multicast cleanup. A timing bug can leave old cleanup work running while a bridge port is removed, causing use-after-free memory access. The public record does not show active exploitation or a CVSS score.

Executive priority

Treat this as a routine but meaningful kernel maintenance item. Prioritize systems that run Linux bridges in production, especially shared infrastructure, virtualization, and network platforms. There is no provided evidence of active exploitation.

Technical view

The Linux bridge multicast path can free a port before prior garbage-collection work and timers have fully completed. Syzbot reported a KASAN slab-use-after-free in br_multicast_port_group_expired. The kernel fix waits for previous cleanup work using flush_work before freeing the port.

Likely exposure

Exposure is most relevant to Linux systems using kernel bridge networking with multicast behavior. Servers, virtualization hosts, containers, or network appliances may be in scope if their kernel line lacks the referenced stable fixes.

Exploitation context

The source describes a syzbot-discovered race/use-after-free. KEV is false, and the provided sources do not claim public exploitation, weaponized exploits, or observed attacks.

Researcher notes

The core bug is a race between bridge multicast garbage collection and port removal. Validation should focus on code lineage or vendor backports, not only version strings, because distributions may carry fixes without matching upstream release numbers.

Mitigation direction

  • Update affected Linux kernels through the system vendor or distribution channel.
  • Ensure the kernel includes one of the referenced upstream stable fixes.
  • For Debian LTS systems, review and apply the cited Debian LTS advisory.
  • Reduce reliance on bridge multicast behavior where it is not operationally needed.
  • Monitor vendor kernel advisories for backported fixes and package version guidance.

Validation and detection

  • Inventory Linux kernel versions across bridge-capable hosts.
  • Identify systems using Linux bridge networking and multicast features.
  • Confirm installed kernels include the relevant stable fix or vendor backport.
  • Review distribution advisories for fixed package versions before closing exposure.
  • Prioritize testing on virtualization, container, and network edge hosts.
Prepared
Confidence
medium
Sources
8

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2024-44934 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
2ADP providers
7Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxe12cec65b5546f19217e26aafb8add6e2fadca18, e12cec65b5546f19217e26aafb8add6e2fadca18, e12cec65b5546f19217e26aafb8add6e2fadca18, e12cec65b5546f19217e26aafb8add6e2fadca18, e12cec65b5546f19217e26aafb8add6e2fadca18unaffected
LinuxLinux5.10, 0, 5.15.165, 6.1.105, 6.6.46, 6.10.5, 6.11affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.