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Fencer Vulns
medium 5.5

CVE-2024-26633 json

ip6_tunnel: fix NEXTHDR_FRAGMENT handling in ip6_tnl_parse_tlv_enc_lim()

published 2024-03-18 2 y ago modified 2026-06-17 4 mo ago also EUVD-2024-23895

cvss
5.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 26%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

ip6_tunnel: fix NEXTHDR_FRAGMENT handling in ip6_tnl_parse_tlv_enc_lim()

syzbot pointed out [1] that NEXTHDR_FRAGMENT handling is broken.

Reading frag_off can only be done if we pulled enough bytes to skb->head. Currently we might access garbage.

[1] BUG: KMSAN: uninit-value in ip6_tnl_parse_tlv_enc_lim+0x94f/0xbb0 ip6_tnl_parse_tlv_enc_lim+0x94f/0xbb0 ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1326 [inline] ip6_tnl_start_xmit+0xab2/0x1a70 net/ipv6/ip6_tunnel.c:1432 __netdev_start_xmit include/linux/netdevice.h:4940 [inline] netdev_start_xmit include/linux/netdevice.h:4954 [inline] xmit_one net/core/dev.c:3548 [inline] dev_hard_start_xmit+0x247/0xa10 net/core/dev.c:3564 __dev_queue_xmit+0x33b8/0x5130 net/core/dev.c:4349 dev_queue_xmit include/linux/netdevice.h:3134 [inline] neigh_connected_output+0x569/0x660 net/core/neighbour.c:1592 neigh_output include/net/neighbour.h:542 [inline] ip6_finish_output2+0x23a9/0x2b30 net/ipv6/ip6_output.c:137 ip6_finish_output+0x855/0x12b0 net/ipv6/ip6_output.c:222 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip6_output+0x323/0x610 net/ipv6/ip6_output.c:243 dst_output include/net/dst.h:451 [inline] ip6_local_out+0xe9/0x140 net/ipv6/output_core.c:155 ip6_send_skb net/ipv6/ip6_output.c:1952 [inline] ip6_push_pending_frames+0x1f9/0x560 net/ipv6/ip6_output.c:1972 rawv6_push_pending_frames+0xbe8/0xdf0 net/ipv6/raw.c:582 rawv6_sendmsg+0x2b66/0x2e70 net/ipv6/raw.c:920 inet_sendmsg+0x105/0x190 net/ipv4/af_inet.c:847 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638 __sys_sendmsg net/socket.c:2667 [inline] __do_sys_sendmsg net/socket.c:2676 [inline] __se_sys_sendmsg net/socket.c:2674 [inline] __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Uninit was created at: slab_post_alloc_hook+0x129/0xa70 mm/slab.h:768 slab_alloc_node mm/slub.c:3478 [inline] __kmem_cache_alloc_node+0x5c9/0x970 mm/slub.c:3517 __do_kmalloc_node mm/slab_common.c:1006 [inline] __kmalloc_node_track_caller+0x118/0x3c0 mm/slab_common.c:1027 kmalloc_reserve+0x249/0x4a0 net/core/skbuff.c:582 pskb_expand_head+0x226/0x1a00 net/core/skbuff.c:2098 __pskb_pull_tail+0x13b/0x2310 net/core/skbuff.c:2655 pskb_may_pull_reason include/linux/skbuff.h:2673 [inline] pskb_may_pull include/linux/skbuff.h:2681 [inline] ip6_tnl_parse_tlv_enc_lim+0x901/0xbb0 net/ipv6/ip6_tunnel.c:408 ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1326 [inline] ip6_tnl_start_xmit+0xab2/0x1a70 net/ipv6/ip6_tunnel.c:1432 __netdev_start_xmit include/linux/netdevice.h:4940 [inline] netdev_start_xmit include/linux/netdevice.h:4954 [inline] xmit_one net/core/dev.c:3548 [inline] dev_hard_start_xmit+0x247/0xa10 net/core/dev.c:3564 __dev_queue_xmit+0x33b8/0x5130 net/core/dev.c:4349 dev_queue_xmit include/linux/netdevice.h:3134 [inline] neigh_connected_output+0x569/0x660 net/core/neighbour.c:1592 neigh_output include/net/neighbour.h:542 [inline] ip6_finish_output2+0x23a9/0x2b30 net/ipv6/ip6_output.c:137 ip6_finish_output+0x855/0x12b0 net/ipv6/ip6_output.c:222 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip6_output+0x323/0x610 net/ipv6/ip6_output.c:243 dst_output include/net/dst.h:451 [inline] ip6_local_out+0xe9/0x140 net/ipv6/output_core.c:155 ip6_send_skb net/ipv6/ip6_output.c:1952 [inline] ip6_push_pending_frames+0x1f9/0x560 net/ipv6/ip6_output.c:1972 rawv6_push_pending_frames+0xbe8/0xdf0 net/ipv6/raw.c:582 rawv6_sendmsg+0x2b66/0x2e70 net/ipv6/raw.c:920 inet_sendmsg+0x105/0x190 net/ipv4/af_inet.c:847 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638 __sys_sendmsg net/socket.c:2667 [inline] __do_sys_sendms ---truncated---

Patch / fix

  • Linux Linux 3.3, 3.11, 3.13, 3.17, 3.19, 4.5, 4.10, 4.19.306, 5.4.268, 5.10.209, 5.15.148, 6.1.75, 6.6.14, 6.7.2, 6.8
  • linux Debian 12 6.1.76-1
  • linux Debian 14, Debian 13 6.6.15-1

debian advisories DEBIAN-CVE-2024-26633

  • linux Ubuntu 20.04 LTS 5.4.0-176.196
  • linux Ubuntu 22.04 LTS 5.15.0-102.112
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1122.132
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1057.63
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1126.135
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1055.63
  • linux-gke Ubuntu 22.04 LTS 5.15.0-1054.59
  • linux-ibm Ubuntu 20.04 LTS 5.4.0-1069.74

ubuntu advisories UBUNTU-CVE-2024-26633

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel RHEL 9 5.14.0-427.13.1.el9_4
  • rv RHEL 9 5.14.0-427.13.1.el9_4
  • perf RHEL 9 5.14.0-427.13.1.el9_4
  • rtla RHEL 9 5.14.0-427.13.1.el9_4
  • bpftool RHEL 9 7.3.0-427.13.1.el9_4
  • libperf RHEL 9 5.14.0-427.13.1.el9_4
  • kernel-rt RHEL 9 5.14.0-427.13.1.el9_4
  • kernel-64k RHEL 9 5.14.0-427.13.1.el9_4

red hat advisories RHSA-2024:2394

  • kernel-rt Linux Micro 6.0 6.4.0-9.1
  • kernel-source-rt Linux Micro 6.0 6.4.0-9.1
  • kernel-source Linux Micro 6.0 6.4.0-18.1
  • kernel-default Linux Micro 6.0 6.4.0-18.1
  • kernel-kvmsmall Linux Micro 6.0 6.4.0-18.1
  • kernel-default-base Linux Micro 6.0 6.4.0-17.1.1.51
  • kernel-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.5.1
  • kernel-syms-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.5.1

suse advisories SUSE-SU-2025:20028-1SUSE-SU-2025:20008-1SUSE-SU-2024:2973-1SUSE-SU-2024:2947-1SUSE-SU-2024:2939-1SUSE-SU-2024:2896-1

  • kernel AlmaLinux 9 5.14.0-427.13.1.el9_4
  • rv AlmaLinux 9 5.14.0-427.13.1.el9_4
  • perf AlmaLinux 9 5.14.0-427.13.1.el9_4
  • rtla AlmaLinux 9 5.14.0-427.13.1.el9_4
  • bpftool AlmaLinux 9 7.3.0-427.13.1.el9_4
  • libperf AlmaLinux 9 5.14.0-427.13.1.el9_4
  • kernel-rt AlmaLinux 9 5.14.0-427.13.1.el9_4
  • kernel-64k AlmaLinux 9 5.14.0-427.13.1.el9_4

almalinux advisories ALSA-2024:2394

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2024-26633 updated cvss 5.5

kernel: ip6_tunnel: fix NEXTHDR_FRAGMENT handling in ip6_tnl_parse_tlv_enc_lim()

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    affected: no fix available
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-427.13.1.el9_4, perf 5.14.0-427.13.1.el9_4, rtla 5.14.0-427.13.1.el9_4, kernel-devel-matched 5.14.0-427.13.1.el9_4, kernel-64k-devel-matched 5.14.0-427.13.1.el9_4, kernel-debug-devel-matched 5.14.0-427.13.1.el9_4, +6 more Red Hat Enterprise Linux BaseOS (v. 9) bpftool 7.3.0-427.13.1.el9_4, kernel 5.14.0-427.13.1.el9_4, kernel-64k 5.14.0-427.13.1.el9_4, kernel-core 5.14.0-427.13.1.el9_4, kernel-tools 5.14.0-427.13.1.el9_4, python3-perf 5.14.0-427.13.1.el9_4, +28 more Red Hat Enterprise Linux CRB (v. 9) libperf 5.14.0-427.13.1.el9_4, kernel-debuginfo-common-s390x 5.14.0-427.13.1.el9_4, kernel-debuginfo-common-x86_64 5.14.0-427.13.1.el9_4, kernel-debuginfo-common-aarch64 5.14.0-427.13.1.el9_4, kernel-debuginfo-common-ppc64le 5.14.0-427.13.1.el9_4 Red Hat Enterprise Linux NFV (v. 9) kernel-rt 5.14.0-427.13.1.el9_4, kernel-rt-kvm 5.14.0-427.13.1.el9_4, kernel-rt-core 5.14.0-427.13.1.el9_4, kernel-rt-modules 5.14.0-427.13.1.el9_4, kernel-rt-debug-kvm 5.14.0-427.13.1.el9_4, kernel-rt-debug-core 5.14.0-427.13.1.el9_4, +6 more Red Hat Enterprise Linux RT (v. 9) kernel-rt 5.14.0-427.13.1.el9_4, kernel-rt-core 5.14.0-427.13.1.el9_4, kernel-rt-modules 5.14.0-427.13.1.el9_4, kernel-rt-debug-core 5.14.0-427.13.1.el9_4, kernel-rt-modules-core 5.14.0-427.13.1.el9_4, kernel-rt-debug-modules 5.14.0-427.13.1.el9_4, +4 more
    fixed: vendor fix RHSA-2024:2394

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.33% chance of exploitation in the next 30 days, higher than 26% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.