CVE-2026-98802
In the Linux kernel, the following vulnerability has been resolved:
seg6: ensure packet data is writable before modifying SRH and IPv6 DA
advance_nextseg() modifies the SRH Segments Left field and the IPv6 destination address without ensuring the packet data is writable. seg6_next_csid_advance_arg() has the same problem when it advances the NEXT-C-SID argument in the destination address.
The skb may be cloned, for example by an AF_PACKET socket receiving on the ingress device. advance_nextseg() and seg6_next_csid_advance_arg() then write into the packet data shared with the clone. A read from that socket can return the modified packet instead of the received one. The simplified path below shows this for advance_nextseg():
Read full descriptionShow less
Call skb_ensure_writable() in advance_nextseg() and in seg6_next_csid_advance_arg() before they modify the packet data. skb_ensure_writable() may reallocate skb->head, which invalidates the pointers into the packet data taken before the call. advance_nextseg() now returns a valid SRH pointer, or NULL if skb_ensure_writable() fails. seg6_next_csid_advance_arg() takes the pointer to the destination address from the skb after skb_ensure_writable(). On failure, the callers drop the packet with SKB_DROP_REASON_NOMEM.
Technical details traces, logs and code from the original report
__netif_receive_skb_one_core
__netif_receive_skb_core
deliver_skb [orig: users=2, cloned=0]
packet_rcv
skb_clone clone queued to the AF_PACKET socket
consume_skb(orig) [orig: users=1, cloned=1]
ipv6_rcv
ip6_rcv_core skb_share_check: no-op [orig: users=1]
[...]
input_action_end_core
advance_nextseg writes into the data shared with the cloneCVSS
NVD hasn't assigned a CVSS score to this CVE (common since the April 2026 policy change).
Exploitation probability (EPSS)
- Probability of exploitation in the next 30 days
- 0.15 %
- Percentile among all scored CVEs
- 4
- Score date
- 10/20/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
Affected technologies (1)
⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.
References
Raw JSON (NVD)
Show
{
"id": "CVE-2026-98802",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "140f04c33bbcf89440dcaf8bef04918abff5a52d",
"lessThan": "e9141fdb7a2ead48cfcd60c681aba91d3014255b",
"versionType": "git"
},
{
"status": "affected",
"version": "140f04c33bbcf89440dcaf8bef04918abff5a52d",
"lessThan": "8ae3f4067ba4ae3a15581392f6dac422e3d3def0",
"versionType": "git"
}
],
"programFiles": [
"net/ipv6/seg6_local.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.14"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.14",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "7.2.10",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/ipv6/seg6_local.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-10-18T16:17:34.250",
"references": [
{
"url": "https://git.kernel.org/stable/c/8ae3f4067ba4ae3a15581392f6dac422e3d3def0",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/e9141fdb7a2ead48cfcd60c681aba91d3014255b",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nseg6: ensure packet data is writable before modifying SRH and IPv6 DA\n\nadvance_nextseg() modifies the SRH Segments Left field and the IPv6\ndestination address without ensuring the packet data is writable.\nseg6_next_csid_advance_arg() has the same problem when it advances the\nNEXT-C-SID argument in the destination address.\n\nThe skb may be cloned, for example by an AF_PACKET socket receiving on\nthe ingress device. advance_nextseg() and seg6_next_csid_advance_arg()\nthen write into the packet data shared with the clone. A read from that\nsocket can return the modified packet instead of the received one. The\nsimplified path below shows this for advance_nextseg():\n\n__netif_receive_skb_one_core\n __netif_receive_skb_core\n deliver_skb [orig: users=2, cloned=0]\n packet_rcv\n skb_clone clone queued to the AF_PACKET socket\n consume_skb(orig) [orig: users=1, cloned=1]\n ipv6_rcv\n ip6_rcv_core skb_share_check: no-op [orig: users=1]\n [...]\n input_action_end_core\n advance_nextseg writes into the data shared with the clone\n\nCall skb_ensure_writable() in advance_nextseg() and in\nseg6_next_csid_advance_arg() before they modify the packet data.\nskb_ensure_writable() may reallocate skb->head, which invalidates the\npointers into the packet data taken before the call.\nadvance_nextseg() now returns a valid SRH pointer, or NULL if\nskb_ensure_writable() fails.\nseg6_next_csid_advance_arg() takes the pointer to the destination\naddress from the skb after skb_ensure_writable().\nOn failure, the callers drop the packet with SKB_DROP_REASON_NOMEM."
}
],
"lastModified": "2026-10-19T10:19:44.260",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}