In the Linux kernel, the following vulnerability has been resolved: ip6_tunnel: use skb_cow_head() in ip6_tnl_xmit() ip6_tnl_xmit() may need to expand headroom before it can push the outer IPv6 and optional encap headers
Why It Matters
Analysis dossierWhy It Matters
In the Linux kernel, the following vulnerability has been resolved: ip6_tunnel: use skb_cow_head() in ip6_tnl_xmit() ip6_tnl_xmit() may need to expand headroom before it can push the outer IPv6 and optional encap headers. It currently does that with skb_realloc_headroom(), copies skb->sk ownership, consumes the original skb, and then continues processing with the replacement skb kept only in its local variable. That is safe only if the helper cannot fail afterwards. But this helper still has post-reallocation error exits. collect_md tunnels reject non-NONE encap after the replacement, and ip6_tnl_encap() can also fail later. In those cases the helper returns an error to its callers while the caller still only has the original skb pointer. Both ip6_tnl_start_xmit() and the IPv6 GRE paths free the caller skb on error, so they can end up freeing an skb that ip6_tnl_xmit() already consumed. Use skb_cow_head() instead. It provides the required headroom and writability without privately replacing the caller-owned skb, so later error returns cannot leave callers with a stale pointer. The Ethernet users, ip6gretap and ip6erspan, clear IFF_TX_SKB_SHARING and already call skb_cow_head() before entering ip6_tnl_xmit(). They do not rely on the removed skb_shared() reallocation. This also makes the IPv6 tunnel path consistent with ip_tunnel_xmit().
High
Unknown
Unknown
Risk basis: SOC ecosystem technology relevance; HIGH severity; No confirmed exploitation signal in current enrichment
Affected Products & Remediation
0 source-backed productsVendor or catalog guidance (source)
Not provided by source
Known exploitation (source facts)
Only what a source states. Unknown means no source has said either way; it is not "not exploited".
- CISA KEV
- Unknown
- Exploited (source statement)
- Unknown
- Publicly disclosed (source)
- Unknown
Suggested hunting (rule-based inference)
SecOps Signal recommendation (rule-based inference). These steps are hunting hypotheses from the vulnerability class; they do not state or imply that exploitation occurred here or anywhere.
Matched local-privilege-escalation (CVSS AV:L, CVSS PR:L)
Exposure
- Identify hosts reporting this CVE, prioritising shared or multi-user systems.Telemetry: DeviceTvmSoftwareVulnerabilities · A local, low-privilege vector matters most where untrusted users can run code. · Rule local-privilege-escalation
Exploitation evidence
- Look for low-privileged processes spawning SYSTEM or root-level child processes on affected hosts.Telemetry: DeviceProcessEvents · Hunting hypothesis from the CVSS vector; privilege transitions are a focused starting point, not evidence of attack. · Rule local-privilege-escalation
Response
- Confirm the source-stated update on affected hosts.Telemetry: DeviceTvmSoftwareVulnerabilities · Host inventory can verify remediation. · Rule local-privilege-escalation
CISA KEV Record
CISA KEV status was not determined for this record.
Change History & Source Data
— No recorded material change
- CNA / source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
- Record status · verification
- UPDATED · NVD API
- CPE
- Unknown
Evidence & Provenance
— No published hunting query names this record. Browse community and library queries instead.
Correlated briefings
— No published briefing references this CVE