Answer in brief
CVE-2026-89563 records a High severity (CVSS 7.8) vulnerability in ip6_tunnel: use skb_cow_head() in ip6_tnl_xmit(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=058214a4d1dfefed9f01a277fadd3590acb5f990 <37df5bc6b5ccad88c2faa0f5466f150178882b74 || >=058214a4d1dfefed9f01a277fadd3590acb5f990 <b36dfd6e8cff00cea81c11cc0af88d1564763461 || >=058214a4d1dfefed9f01a277fadd3590acb5f990 <8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52 || >=058214a4d1dfefed9f01a277fadd3590acb5f990 <87f21b59ddc618eff9670c174842964ad65fdade | 37df5bc6b5ccad88c2faa0f5466f150178882b74, b36dfd6e8cff00cea81c11cc0af88d1564763461, 8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52, 87f21b59ddc618eff9670c174842964ad65fdade |
| Linux/Linuxgeneric | 4.7 | Not reported |
| Linux/Linuxgeneric | >=058214a4d1dfefed9f01a277fadd3590acb5f990 <6e8eff8ed13b14708bc39f170144eacde494aac6 || >=058214a4d1dfefed9f01a277fadd3590acb5f990 <dc1a319a4815c074914e2812e0e9cd0164ca682b || >=058214a4d1dfefed9f01a277fadd3590acb5f990 <629d5557e635cdbc109a14ed913ba5a540e3f79a || >=058214a4d1dfefed9f01a277fadd3590acb5f990 <defa0adeff132cc90ed66915b9a104d9393e1e54 || >=058214a4d1dfefed9f01a277fadd3590acb5f990 <37df5bc6b5ccad88c2faa0f5466f150178882b74 || >=058214a4d1dfefed9f01a277fadd3590acb5f990 <b36dfd6e8cff00cea81c11cc0af88d1564763461 || >=058214a4d1dfefed9f01a277fadd3590acb5f990 <8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52 || >=058214a4d1dfefed9f01a277fadd3590acb5f990 <87f21b59ddc618eff9670c174842964ad65fdade | 6e8eff8ed13b14708bc39f170144eacde494aac6, dc1a319a4815c074914e2812e0e9cd0164ca682b, 629d5557e635cdbc109a14ed913ba5a540e3f79a, defa0adeff132cc90ed66915b9a104d9393e1e54, 37df5bc6b5ccad88c2faa0f5466f150178882b74, b36dfd6e8cff00cea81c11cc0af88d1564763461, 8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52, 87f21b59ddc618eff9670c174842964ad65fdade |
Published upstream
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 11, 2026
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().
Quoted source text, attributed separately from HOL analysis.