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6lowpan: fix off-by-one in multicast context address compression

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: 6lowpan: fix off-by-one in multicast context address compression The second memcpy in lowpan_iphc_mcast_ctx_addr_compress() uses &data[1] as destination and &ipaddr->s6_addr[11] as source, but both should be offset by one: &data[2] and &ipaddr->s6_addr[12] respectively. This off-by-one has two consequences: 1. data[1] is overwritten with s6_addr[11], corrupting the RIID field in the compressed multicast address 2. data[5] is never written, so uninitialized kernel stack memory is transmitted over the network via lowpan_push_hc_data(), leaking kernel stack contents The correct inline data layout must match what the decompression function lowpan_uncompress_multicast_ctx_daddr() expects: data[0..1] = s6_addr[1..2] (flags/scope + RIID) data[2..5] = s6_addr[12..15] (group ID) Also zero-initialize the data array as a defensive measure against similar bugs in the future.

Products
Kernel
Affected versions
Not specified
Fixed versions
5.10.259, 5.15.210, 6.1.176, 6.12.94, 6.18.36, 6.6.143, 7.0.13
CVEs
CVE-2026-53263
Confirmed fixed CVEs
Not specified
Updated in this feed
4 Nov 2026, 21:36 UTC · Revision 1

Source evidence

6lowpan: fix off-by-one in multicast context address compression

core-osv · Original source

Published 25 Jun 2026, 08:39 UTC

In the Linux kernel, the following vulnerability has been resolved: 6lowpan: fix off-by-one in multicast context address compression The second memcpy in lowpan_iphc_mcast_ctx_addr_compress() uses &data[1] as destination and &ipaddr->s6_addr[11] as source, but both should be offset by one: &data[2] and &ipaddr->s6_addr[12] respectively. This off-by-one has two consequences: 1. data[1] is overwritten with s6_addr[11], corrupting the RIID field in the compressed multicast address 2. data[5] is never written, so uninitialized kernel stack memory is transmitted over the network via lowpan_push_hc_data(), leaking kernel stack contents The correct inline data layout must match what the decompression function lowpan_uncompress_multicast_ctx_daddr() expects: data[0..1] = s6_addr[1..2] (flags/scope + RIID) data[2..5] = s6_addr[12..15] (group ID) Also zero-initialize the data array as a defensive measure against similar bugs in the future.

osv:CVE-2026-53263

Kernel

Fixed versions: 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.94, 6.18.36, 7.0.13

Complete source record
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  "url": "https://osv.dev/vulnerability/CVE-2026-53263",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "6lowpan: fix off-by-one in multicast context address compression",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: 6lowpan: fix off-by-one in multicast context address compression The second memcpy in lowpan_iphc_mcast_ctx_addr_compress() uses &data[1] as destination and &ipaddr->s6_addr[11] as source, but both should be offset by one: &data[2] and &ipaddr->s6_addr[12] respectively. This off-by-one has two consequences: 1. data[1] is overwritten with s6_addr[11], corrupting the RIID field in the compressed multicast address 2. data[5] is never written, so uninitialized kernel stack memory is transmitted over the network via lowpan_push_hc_data(), leaking kernel stack contents The correct inline data layout must match what the decompression function lowpan_uncompress_multicast_ctx_daddr() expects: data[0..1] = s6_addr[1..2] (flags/scope + RIID) data[2..5] = s6_addr[12..15] (group ID) Also zero-initialize the data array as a defensive measure against similar bugs in the future.",
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      "modified": "2026-10-28T02:30:39.975769585Z",
      "provider": "osv",
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  "source_id": "core-osv",
  "document_id": 507373,
  "published_at": "2026-06-25T08:39:51.215+00:00"
}