CVE-2026-98802
seg6: ensure packet data is writable before modifying SRH and IPv6 DA
Description
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(): __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 clone 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.
INFO
Published Date :
Oct. 18, 2026, 4:17 p.m.
Last Modified :
Oct. 18, 2026, 4:17 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
- Call skb_ensure_writable() before modifying packet data.
- Drop packets on skb_ensure_writable() failure.
- Update kernel to apply fixes.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-98802.
| URL | Resource |
|---|---|
| https://git.kernel.org/stable/c/8ae3f4067ba4ae3a15581392f6dac422e3d3def0 | |
| https://git.kernel.org/stable/c/e9141fdb7a2ead48cfcd60c681aba91d3014255b |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-98802 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-98802
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-98802 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-98802 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Oct. 18, 2026
Action Type Old Value New Value Added Description 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(): __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 clone 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. Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/98xxx/CVE-2026-98802.json">CVE-2026-98802</a> Added Reference https://git.kernel.org/stable/c/8ae3f4067ba4ae3a15581392f6dac422e3d3def0 Added Reference https://git.kernel.org/stable/c/e9141fdb7a2ead48cfcd60c681aba91d3014255b