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CVE Record

CVE-2024-26631: ipv6: mcast: fix data-race in ipv6_mc_down / mld_ifc_work

In the Linux kernel, the following vulnerability has been resolved: ipv6: mcast: fix data-race in ipv6_mc_down / mld_ifc_work idev->mc_ifc_count can be written over without proper locking. Originally found by syzbot [1], fix this issue by encapsulating calls to mld_ifc_stop_work() (and mld_gq_stop_work() for good measure) with mutex_lock() and mutex_unlock() accordingly as these functions should only be called with mc_lock per their declarations. [1] BUG: KCSAN: data-race in ipv6_mc_down / mld_ifc_work write to 0xffff88813a80c832 of 1 bytes by task 3771 on cpu 0: mld_ifc_stop_work net/ipv6/mcast.c:1080 [inline] ipv6_mc_down+0x10a/0x280 net/ipv6/mcast.c:2725 addrconf_ifdown+0xe32/0xf10 net/ipv6/addrconf.c:3949 addrconf_notify+0x310/0x980 notifier_call_chain kernel/notifier.c:93 [inline] raw_notifier_call_chain+0x6b/0x1c0 kernel/notifier.c:461 __dev_notify_flags+0x205/0x3d0 dev_change_flags+0xab/0xd0 net/core/dev.c:8685 do_setlink+0x9f6/0x2430 net/core/rtnetlink.c:2916 rtnl_group_changelink net/core/rtnetlink.c:3458 [inline] __rtnl_newlink net/core/rtnetlink.c:3717 [inline] rtnl_newlink+0xbb3/0x1670 net/core/rtnetlink.c:3754 rtnetlink_rcv_msg+0x807/0x8c0 net/core/rtnetlink.c:6558 netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2545 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6576 netlink_unicast_kernel net/netlink/af_netlink.c:1342 [inline] netlink_unicast+0x589/0x650 net/netlink/af_netlink.c:1368 netlink_sendmsg+0x66e/0x770 net/netlink/af_netlink.c:1910 ... write to 0xffff88813a80c832 of 1 bytes by task 22 on cpu 1: mld_ifc_work+0x54c/0x7b0 net/ipv6/mcast.c:2653 process_one_work kernel/workqueue.c:2627 [inline] process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2700 worker_thread+0x525/0x730 kernel/workqueue.c:2781 ...

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux IPv6 multicast race allows shared state to be changed concurrently without required locking. The supplied 7.8 CVSS assessment indicates potentially severe confidentiality, integrity, and availability impact. Exploitation is local, requires low privileges, and needs no user interaction; it is not described as remotely exploitable.

Executive priority

Treat this as a high-priority kernel update for multi-user or less-trusted Linux systems. Schedule vendor-supported remediation promptly. Current evidence does not justify an emergency internet-wide response because the described attack vector is local and active exploitation is unsupported.

Technical view

Concurrent writes to idev->mc_ifc_count occur between ipv6_mc_down and mld_ifc_work on separate tasks or CPUs. The upstream correction protects calls to mld_ifc_stop_work and mld_gq_stop_work with mc_lock, matching their locking requirements.

Likely exposure

The bundle lists Linux kernel 5.13 and entries through 6.8 as affected, but provides neither distribution package mappings nor unambiguous range boundaries. Exposure is most relevant on affected systems where a low-privileged local user can reach the implicated IPv6 interface and multicast paths.

Exploitation context

The bundle marks this CVE as absent from KEV and provides no evidence of active exploitation. Syzbot discovered the race using KCSAN. The supplied CVSS vector describes local, low-complexity exploitation requiring low privileges and no user interaction, but the sources do not establish practical exploit reliability.

Researcher notes

The evidence demonstrates a same-byte write race across CPUs and identifies the missing mutex protection. It does not provide a CWE, concrete corruption outcome, exploit proof, affected distribution packages, or clear version-range operators. Those gaps limit conclusions about practical exploitation and exact fleet exposure.

Mitigation direction

  • Install a vendor kernel containing the applicable referenced Linux stable fix for your kernel branch.
  • Check distribution or appliance vendor guidance to map packaged kernel versions to the upstream fixes.
  • Prioritize systems granting local access to less-trusted users.
  • Ensure systems are running the updated kernel after installation.

Validation and detection

  • Inventory active kernel versions and compare them with vendor-specific affected and fixed package guidance.
  • Confirm vendor changelogs reference CVE-2024-26631 or an applicable upstream stable commit.
  • Verify the active kernel changed to the remediated build after maintenance.
  • Review local account exposure while remediation remains pending.
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-2024-26631 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

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

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.

1CVSS vectors
3Timeline events
2ADP providers
7Source links

SSVC decision data

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

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2024-26631Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

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

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux07a7a183f22cf1e3ce5ed336fe62a6248a2f6738, 2d9a93b4902be6a5504b5941dd15e9cd776aadca, 2d9a93b4902be6a5504b5941dd15e9cd776aadca, 2d9a93b4902be6a5504b5941dd15e9cd776aadca, 2d9a93b4902be6a5504b5941dd15e9cd776aadca, 2d9a93b4902be6a5504b5941dd15e9cd776aadcaunaffected
LinuxLinux5.13, 0, 5.15.148, 6.1.75, 6.6.14, 6.7.2, 6.8affected
Weakness

CWE details

No CWE listed

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