CVE-2026-89563
CVE CVE-2026-89563EUVD EUVD-2026-76474Published 2026-09-11T19:44:34.000ZLast changed 2026-09-14T12:01:03.000ZCVSS 7.8
What the advisory describes
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().
Source: EUVD (ENISA), in the words of the advisory.
Products the advisory names
These come from the advisory itself, not from any check we performed.
- Linux — Linux patch: 5.10.270; patch: 6.6.157; patch: 5.15.221; 058214a4d1dfefed9f01a277fadd3590acb5f990 <629d5557e635cdbc109a14ed913ba5a540e3f79a; 058214a4d1dfefed9f01a277fadd3590acb5f990 <8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52; 4.7; patch: 7.2.4; 058214a4d1dfefed9f01a277fadd3590acb5f990 <defa0adeff132cc90ed66915b9a104d9393e1e54; 058214a4d1dfefed9f01a277fadd3590acb5f990 <87f21b59ddc618eff9670c174842964ad65fdade; patch: 6.1.188; 058214a4d1dfefed9f01a277fadd3590acb5f990 <37df5bc6b5ccad88c2faa0f5466f150178882b74; patch: 6.18.50; 058214a4d1dfefed9f01a277fadd3590acb5f990 <b36dfd6e8cff00cea81c11cc0af88d1564763461; 058214a4d1dfefed9f01a277fadd3590acb5f990 <dc1a319a4815c074914e2812e0e9cd0164ca682b; patch: 7.3-rc1; patch: 0; 058214a4d1dfefed9f01a277fadd3590acb5f990 <6e8eff8ed13b14708bc39f170144eacde494aac6; patch: 6.12.109
The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.
Carried in the product catalogue
An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.
- Linux — Linux
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