{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-89563", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.725Z", "datePublished": "2026-09-11T19:44:34.375Z", "dateUpdated": "2026-09-11T19:44:34.375Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-09-11T19:44:34.375Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nip6_tunnel: use skb_cow_head() in ip6_tnl_xmit()\n\nip6_tnl_xmit() may need to expand headroom before it can push the\nouter IPv6 and optional encap headers. It currently does that with\nskb_realloc_headroom(), copies skb->sk ownership, consumes the original\nskb, and then continues processing with the replacement skb kept only in\nits local variable.\n\nThat is safe only if the helper cannot fail afterwards. But this helper\nstill has post-reallocation error exits. collect_md tunnels reject\nnon-NONE encap after the replacement, and ip6_tnl_encap() can also fail\nlater. In those cases the helper returns an error to its callers while\nthe caller still only has the original skb pointer.\n\nBoth ip6_tnl_start_xmit() and the IPv6 GRE paths free the caller skb on\nerror, so they can end up freeing an skb that ip6_tnl_xmit() already\nconsumed.\n\nUse skb_cow_head() instead. It provides the required headroom and\nwritability without privately replacing the caller-owned skb, so later\nerror returns cannot leave callers with a stale pointer.\n\nThe Ethernet users, ip6gretap and ip6erspan, clear IFF_TX_SKB_SHARING\nand already call skb_cow_head() before entering ip6_tnl_xmit(). They do\nnot rely on the removed skb_shared() reallocation. This also makes the\nIPv6 tunnel path consistent with ip_tunnel_xmit()."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/ipv6/ip6_tunnel.c"], "versions": [{"version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "37df5bc6b5ccad88c2faa0f5466f150178882b74", "status": "affected", "versionType": "git"}, {"version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "b36dfd6e8cff00cea81c11cc0af88d1564763461", "status": "affected", "versionType": "git"}, {"version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52", "status": "affected", "versionType": "git"}, {"version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "87f21b59ddc618eff9670c174842964ad65fdade", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/ipv6/ip6_tunnel.c"], "versions": [{"version": "4.7", "status": "affected"}, {"version": "0", "lessThan": "4.7", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3-rc1", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.7", "versionEndExcluding": "6.12.109"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.7", "versionEndExcluding": "6.18.50"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.7", "versionEndExcluding": "7.2.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.7", "versionEndExcluding": "7.3-rc1"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/37df5bc6b5ccad88c2faa0f5466f150178882b74"}, {"url": "https://git.kernel.org/stable/c/b36dfd6e8cff00cea81c11cc0af88d1564763461"}, {"url": "https://git.kernel.org/stable/c/8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52"}, {"url": "https://git.kernel.org/stable/c/87f21b59ddc618eff9670c174842964ad65fdade"}], "title": "ip6_tunnel: use skb_cow_head() in ip6_tnl_xmit()", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/ipv6/ip6_tunnel.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "37df5bc6b5ccad88c2faa0f5466f150178882b74", "status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "versionType": "git"}, {"lessThan": "b36dfd6e8cff00cea81c11cc0af88d1564763461", "status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "versionType": "git"}, {"lessThan": "8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52", "status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "versionType": "git"}, {"lessThan": "87f21b59ddc618eff9670c174842964ad65fdade", "status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/ipv6/ip6_tunnel.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "4.7"}, {"lessThan": "4.7", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.109", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.50", "versionType": "semver"}, {"lessThanOrEqual": "7.2.*", "status": "unaffected", "version": "7.2.4", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.3-rc1", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nip6_tunnel: use skb_cow_head() in ip6_tnl_xmit()\n\nip6_tnl_xmit() may need to expand headroom before it can push the\nouter IPv6 and optional encap headers. It currently does that with\nskb_realloc_headroom(), copies skb->sk ownership, consumes the original\nskb, and then continues processing with the replacement skb kept only in\nits local variable.\n\nThat is safe only if the helper cannot fail afterwards. But this helper\nstill has post-reallocation error exits. collect_md tunnels reject\nnon-NONE encap after the replacement, and ip6_tnl_encap() can also fail\nlater. In those cases the helper returns an error to its callers while\nthe caller still only has the original skb pointer.\n\nBoth ip6_tnl_start_xmit() and the IPv6 GRE paths free the caller skb on\nerror, so they can end up freeing an skb that ip6_tnl_xmit() already\nconsumed.\n\nUse skb_cow_head() instead. It provides the required headroom and\nwritability without privately replacing the caller-owned skb, so later\nerror returns cannot leave callers with a stale pointer.\n\nThe Ethernet users, ip6gretap and ip6erspan, clear IFF_TX_SKB_SHARING\nand already call skb_cow_head() before entering ip6_tnl_xmit(). They do\nnot rely on the removed skb_shared() reallocation. This also makes the\nIPv6 tunnel path consistent with ip_tunnel_xmit()."}], "id": "CVE-2026-89563", "lastModified": "2026-09-11T20:19:40.193", "metrics": {}, "published": "2026-09-11T20:19:40.193", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/37df5bc6b5ccad88c2faa0f5466f150178882b74"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/87f21b59ddc618eff9670c174842964ad65fdade"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/b36dfd6e8cff00cea81c11cc0af88d1564763461"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: Linux Kernel: Memory corruption in ip6_tunnel due to double-free vulnerability", "id": "2532305", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2532305"}, "csaw": false, "cvss3": {"cvss3_base_score": "4.4", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-1341", "details": ["A flaw was found in the `ip6_tunnel` module of the Linux kernel. Incorrect handling of socket buffers (skb) during headroom reallocation in the `ip6_tnl_xmit()` function can lead to a double-free vulnerability. This occurs when an error path is taken after the original skb has been consumed, but the caller still holds a pointer to it, potentially allowing the same memory to be freed twice. This memory corruption issue could lead to a denial of service or potentially arbitrary code execution."], "name": "CVE-2026-89563", "public_date": "2026-09-11T19:44:34Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-89563\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-89563\nhttps://git.kernel.org/stable/c/37df5bc6b5ccad88c2faa0f5466f150178882b74\nhttps://git.kernel.org/stable/c/87f21b59ddc618eff9670c174842964ad65fdade\nhttps://git.kernel.org/stable/c/8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52\nhttps://git.kernel.org/stable/c/b36dfd6e8cff00cea81c11cc0af88d1564763461"], "threat_severity": "Moderate"}

{}