CVE-2026-43501

Aliases:UBUNTU-CVE-2026-43501DEBIAN-CVE-2026-43501
Advisory lineage Upstream: 0 Downstream: 167
Modified
Published: 21 May 2026, 12:17
Last modified:08 Sept 2026, 08:48

Vulnerability Summary

Overall Risk (default)
high
70/100
CVSS Score
9.8 CRITICAL
v3.1 (cve.org)
EPSS Score
0.65% LOW
1% probability +0.05%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

21 May 2026, 12:17
Published
Vulnerability first disclosed
08 Sept 2026, 08:48
Last Modified
Vulnerability information updated

Description

In the Linux kernel, the following vulnerability has been resolved: ipv6: rpl: reserve mac_len headroom when recompressed SRH grows ipv6_rpl_srh_rcv() decompresses an RFC 6554 Source Routing Header, swaps the next segment into ipv6_hdr->daddr, recompresses, then pulls the old header and pushes the new one plus the IPv6 header back. The recompressed header can be larger than the received one when the swap reduces the common-prefix length the segments share with daddr (CmprI=0, CmprE>0, seg[0][0] != daddr[0] gives the maximum +8 bytes). pskb_expand_head() was gated on segments_left == 0, so on earlier segments the push consumed unchecked headroom. Once skb_push() leaves fewer than skb->mac_len bytes in front of data, skb_mac_header_rebuild()'s call to: skb_set_mac_header(skb, -skb->mac_len); will store (data - head) - mac_len into the u16 mac_header field, which wraps to ~65530, and the following memmove() writes mac_len bytes ~64KiB past skb->head. A single AF_INET6/SOCK_RAW/IPV6_HDRINCL packet over lo with a two segment type-3 SRH (CmprI=0, CmprE=15) reaches headroom 8 after one pass; KASAN reports a 14-byte OOB write in ipv6_rthdr_rcv. Fix this by expanding the head whenever the remaining room is less than the push size plus mac_len, and request that much extra so the rebuilt MAC header fits afterwards.

CVSS Metrics

  • v4.0•CRITICAL•Score: 9.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
  • v3.1•CRITICAL•Score: 9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Trends

Current EPSS score: 0.65%• Percentile: 50%

Techniques & Countermeasures

  • CWE-787•Out-of-bounds Write

    The product writes data past the end, or before the beginning, of the intended buffer.

  • CWE-131•Incorrect Calculation of Buffer Size

    The product does not correctly calculate the size to be used when allocating a buffer, which could lead to a buffer overflow.

Affected Systems

  • debian•linux

    < 5.10.259-1 | < 6.1.176-1 | < 6.12.86-1 | < 7.0.4-1

  • debian•linux-6.1

    < 6.1.176-1~deb11u1

  • ubuntu•linux

    < 5.15.0-185.195 | < 6.8.0-134.134 | < 6.17.0-40.40 | < 7.0.0-27.27

  • ubuntu•linux-allwinner-5.19

    all

  • ubuntu•linux-aws

    < 5.15.0-1111.118 | < 6.8.0-1060.63 | < 6.17.0-1019.19 | < 7.0.0-1008.8

  • ubuntu•linux-aws-5.0

    all

  • ubuntu•linux-aws-5.11

    all

  • ubuntu•linux-aws-5.13

    all

  • ubuntu•linux-aws-5.15

    < 5.15.0-1111.118~20.04.1

  • ubuntu•linux-aws-5.19

    all

  • ubuntu•linux-aws-5.3

    all

  • ubuntu•linux-aws-5.8

    all

  • ubuntu•linux-aws-6.14

    all

  • ubuntu•linux-aws-6.17

    < 6.17.0-1019.19~24.04.1

  • ubuntu•linux-aws-6.2

    all

  • ubuntu•linux-aws-6.5

    all

  • ubuntu•linux-aws-6.8

    < 6.8.0-1060.63~22.04.1

  • ubuntu•linux-aws-fips

    all | < 5.15.0-1111.118+fips1 | < 6.8.0-1060.63+fips1

  • ubuntu•linux-azure

    all | < 5.15.0-1116.125 | < 6.8.0-1063.71 | all | < 7.0.0-1010.10

  • ubuntu•linux-azure-5.11

    all

  • ubuntu•linux-azure-5.13

    all

  • ubuntu•linux-azure-5.15

    < 5.15.0-1116.125~20.04.1

  • ubuntu•linux-azure-5.19

    all

  • ubuntu•linux-azure-5.3

    all

  • ubuntu•linux-azure-5.8

    all

  • ubuntu•linux-azure-6.11

    all

  • ubuntu•linux-azure-6.14

    all

  • ubuntu•linux-azure-6.17

    < 6.17.0-1021.21~24.04.1

  • ubuntu•linux-azure-6.2

    all

  • ubuntu•linux-azure-6.5

    all

  • ubuntu•linux-azure-6.8

    < 6.8.0-1063.71~22.04.1

  • ubuntu•linux-azure-edge

    all

  • ubuntu•linux-azure-fde

    all | all | < 6.8.0-1062.69 | all | < 7.0.0-1009.9

  • ubuntu•linux-azure-fde-5.15

    < 5.15.0-1116.125~20.04.1

  • ubuntu•linux-azure-fde-5.19

    all

  • ubuntu•linux-azure-fde-6.14

    all

  • ubuntu•linux-azure-fde-6.2

    all

  • ubuntu•linux-azure-fde-6.8

    < 6.8.0-1062.69~22.04.1

  • ubuntu•linux-azure-fips

    all | < 5.15.0-1116.125+fips1 | < 6.8.0-1062.69+fips1

  • ubuntu•linux-azure-nvidia

    all

  • ubuntu•linux-azure-nvidia-6.14

    all

  • ubuntu•linux-bluefield

    all | < 5.15.0-1095.97 | < 6.8.0-1026.30

  • ubuntu•linux-fips

    all | < 5.15.0-185.195+fips1 | < 6.8.0-134.134+fips1

  • ubuntu•linux-gcp

    all | < 5.15.0-1111.121 | < 6.8.0-1063.69 | < 6.17.0-1020.22 | < 7.0.0-1007.7

  • ubuntu•linux-gcp-5.11

    all

  • ubuntu•linux-gcp-5.13

    all

  • ubuntu•linux-gcp-5.15

    < 5.15.0-1111.121~20.04.1

  • ubuntu•linux-gcp-5.19

    all

  • ubuntu•linux-gcp-5.3

    all

  • ubuntu•linux-gcp-5.8

    all

Showing first 50 affected entries in server-rendered view.

References (55)