ip6_tunnel: use skb_cow_head() in ip6_tnl_xmit()
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().
CVE-2026-89563
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-89563
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "058214a4d1dfefed9f01a277fadd3590acb5f990",
"lessThan": "6e8eff8ed13b14708bc39f170144eacde494aac6",
"versionType": "git"
},
{
"status": "affected",
"version": "058214a4d1dfefed9f01a277fadd3590acb5f990",
"lessThan": "dc1a319a4815c074914e2812e0e9cd0164ca682b",
"versionType": "git"
},
{
"status": "affected",
"version": "058214a4d1dfefed9f01a277fadd3590acb5f990",
"lessThan": "629d5557e635cdbc109a14ed913ba5a540e3f79a",
"versionType": "git"
},
{
"status": "affected",
"version": "058214a4d1dfefed9f01a277fadd3590acb5f990",
"lessThan": "defa0adeff132cc90ed66915b9a104d9393e1e54",
"versionType": "git"
},
{
"status": "affected",
"version": "058214a4d1dfefed9f01a277fadd3590acb5f990",
"lessThan": "37df5bc6b5ccad88c2faa0f5466f150178882b74",
"versionType": "git"
},
{
"status": "affected",
"version": "058214a4d1dfefed9f01a277fadd3590acb5f990",
"lessThan": "b36dfd6e8cff00cea81c11cc0af88d1564763461",
"versionType": "git"
},
{
"status": "affected",
"version": "058214a4d1dfefed9f01a277fadd3590acb5f990",
"lessThan": "8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52",
"versionType": "git"
},
{
"status": "affected",
"version": "058214a4d1dfefed9f01a277fadd3590acb5f990",
"lessThan": "87f21b59ddc618eff9670c174842964ad65fdade",
"versionType": "git"
}
],
"programFiles": [
"net/ipv6/ip6_tunnel.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.7"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.7",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.270",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.221",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.188",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.157",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.109",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.50",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.4",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/ipv6/ip6_tunnel.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-89563
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #35077 · Revision 1
- Added to Heist Feed
- Publisher date