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CVE Record

CVE-2023-53365: ip6mr: Fix skb_under_panic in ip6mr_cache_report()

In the Linux kernel, the following vulnerability has been resolved: ip6mr: Fix skb_under_panic in ip6mr_cache_report() skbuff: skb_under_panic: text:ffffffff88771f69 len:56 put:-4 head:ffff88805f86a800 data:ffff887f5f86a850 tail:0x88 end:0x2c0 dev:pim6reg ------------[ cut here ]------------ kernel BUG at net/core/skbuff.c:192! invalid opcode: 0000 [#1] PREEMPT SMP KASAN CPU: 2 PID: 22968 Comm: kworker/2:11 Not tainted 6.5.0-rc3-00044-g0a8db05b571a #236 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 Workqueue: ipv6_addrconf addrconf_dad_work RIP: 0010:skb_panic+0x152/0x1d0 Call Trace: <TASK> skb_push+0xc4/0xe0 ip6mr_cache_report+0xd69/0x19b0 reg_vif_xmit+0x406/0x690 dev_hard_start_xmit+0x17e/0x6e0 __dev_queue_xmit+0x2d6a/0x3d20 vlan_dev_hard_start_xmit+0x3ab/0x5c0 dev_hard_start_xmit+0x17e/0x6e0 __dev_queue_xmit+0x2d6a/0x3d20 neigh_connected_output+0x3ed/0x570 ip6_finish_output2+0x5b5/0x1950 ip6_finish_output+0x693/0x11c0 ip6_output+0x24b/0x880 NF_HOOK.constprop.0+0xfd/0x530 ndisc_send_skb+0x9db/0x1400 ndisc_send_rs+0x12a/0x6c0 addrconf_dad_completed+0x3c9/0xea0 addrconf_dad_work+0x849/0x1420 process_one_work+0xa22/0x16e0 worker_thread+0x679/0x10c0 ret_from_fork+0x28/0x60 ret_from_fork_asm+0x11/0x20 When setup a vlan device on dev pim6reg, DAD ns packet may sent on reg_vif_xmit(). reg_vif_xmit() ip6mr_cache_report() skb_push(skb, -skb_network_offset(pkt));//skb_network_offset(pkt) is 4 And skb_push declared as: void *skb_push(struct sk_buff *skb, unsigned int len); skb->data -= len; //0xffff88805f86a84c - 0xfffffffc = 0xffff887f5f86a850 skb->data is set to 0xffff887f5f86a850, which is invalid mem addr, lead to skb_push() fails.

MediumCVSS 5.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2023-53365 is a Linux kernel denial-of-service issue in IPv6 multicast routing handling. Under a specific pim6reg VLAN and IPv6 DAD packet path, the kernel can hit an skb_under_panic BUG and crash. The sources indicate availability impact only, not data theft or privilege escalation.

Executive priority

Treat this as a moderate-priority availability risk. It is not described as data compromise, but kernel crashes can disrupt critical services. Patch through normal Linux kernel update channels, with faster handling for exposed network infrastructure, shared systems, or hosts using advanced IPv6 multicast routing.

Technical view

The flaw is in ip6mr_cache_report(). When a VLAN device is set up on pim6reg, reg_vif_xmit() can reach skb_push() with an invalid negative-derived length, corrupting skb data positioning and triggering skb_under_panic. CVSS is 5.5: local attack vector, low complexity, low privileges, no user interaction, high availability impact.

Likely exposure

Exposure is most likely on Linux systems running affected kernel versions with IPv6 multicast routing/pim6reg behavior and VLAN interactions. The CVE record marks Linux as affected across listed kernel versions and references stable kernel fixes. Generic servers without this networking configuration are likely lower risk, but should still be checked through kernel inventory.

Exploitation context

The source bundle provides no evidence of active exploitation, and KEV is false. The CVSS vector requires local access with low privileges. The described failure was observed in a QEMU test context during IPv6 address configuration work, not as a documented remote exploit path.

Researcher notes

Evidence supports a kernel BUG in the IPv6 multicast routing report path caused by invalid skb_push handling. The source bundle does not provide exploit code, public exploitation, or broad remote reachability. Validation should focus on kernel lineage, stable patch presence, and whether pim6reg/VLAN/IPv6 DAD paths are plausible in the environment.

Mitigation direction

  • Update to a vendor kernel containing the referenced Linux stable fixes.
  • Check Linux distribution advisories for the exact fixed package version.
  • Prioritize systems using IPv6 multicast routing, pim6reg, VLANs, or multi-user local access.
  • If patching is delayed, consult vendor guidance before changing networking behavior.
  • Do not run direct kernel workarounds unless validated by the platform vendor.

Validation and detection

  • Inventory Linux kernel versions across affected hosts.
  • Compare installed kernels against vendor advisories and referenced stable commits.
  • Identify hosts using IPv6 multicast routing, pim6reg, or related VLAN configurations.
  • Confirm patched systems no longer run affected kernel builds.
  • Review crash logs for skb_under_panic or ip6mr_cache_report traces.
Prepared
Confidence
high
Sources
10

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

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CVE-2023-53365 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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
1ADP providers
9Source 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
5.5CVSS 3.1MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H1.83.6CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

5.5Medium
CVSS 3.1 vector shape for CVE-2023-53365Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux14fb64e1f449ef6666f1c3a3fa4e13aec669b98d, 14fb64e1f449ef6666f1c3a3fa4e13aec669b98d, 14fb64e1f449ef6666f1c3a3fa4e13aec669b98d, 14fb64e1f449ef6666f1c3a3fa4e13aec669b98d, 14fb64e1f449ef6666f1c3a3fa4e13aec669b98d, 14fb64e1f449ef6666f1c3a3fa4e13aec669b98d, 14fb64e1f449ef6666f1c3a3fa4e13aec669b98d, 14fb64e1f449ef6666f1c3a3fa4e13aec669b98dunaffected
LinuxLinux2.6.26, 0, 4.14.322, 4.19.291, 5.4.253, 5.10.190, 5.15.126, 6.1.45, 6.4.10, 6.5affected
Weakness

CWE details

No CWE listed

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