GHSA-X3J5-9GHR-8CWM
Vulnerability from github – Published: 2026-03-26 12:30 – Updated: 2026-07-14 15:31In the Linux kernel, the following vulnerability has been resolved:
icmp: fix NULL pointer dereference in icmp_tag_validation()
icmp_tag_validation() unconditionally dereferences the result of rcu_dereference(inet_protos[proto]) without checking for NULL. The inet_protos[] array is sparse -- only about 15 of 256 protocol numbers have registered handlers. When ip_no_pmtu_disc is set to 3 (hardened PMTU mode) and the kernel receives an ICMP Fragmentation Needed error with a quoted inner IP header containing an unregistered protocol number, the NULL dereference causes a kernel panic in softirq context.
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] RIP: 0010:icmp_unreach (net/ipv4/icmp.c:1085 net/ipv4/icmp.c:1143) Call Trace: icmp_rcv (net/ipv4/icmp.c:1527) ip_protocol_deliver_rcu (net/ipv4/ip_input.c:207) ip_local_deliver_finish (net/ipv4/ip_input.c:242) ip_local_deliver (net/ipv4/ip_input.c:262) ip_rcv (net/ipv4/ip_input.c:573) __netif_receive_skb_one_core (net/core/dev.c:6164) process_backlog (net/core/dev.c:6628) handle_softirqs (kernel/softirq.c:561)
Add a NULL check before accessing icmp_strict_tag_validation. If the protocol has no registered handler, return false since it cannot perform strict tag validation.
{
"affected": [],
"aliases": [
"CVE-2026-23398"
],
"database_specific": {
"cwe_ids": [
"CWE-476"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-03-26T11:16:19Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nicmp: fix NULL pointer dereference in icmp_tag_validation()\n\nicmp_tag_validation() unconditionally dereferences the result of\nrcu_dereference(inet_protos[proto]) without checking for NULL.\nThe inet_protos[] array is sparse -- only about 15 of 256 protocol\nnumbers have registered handlers. When ip_no_pmtu_disc is set to 3\n(hardened PMTU mode) and the kernel receives an ICMP Fragmentation\nNeeded error with a quoted inner IP header containing an unregistered\nprotocol number, the NULL dereference causes a kernel panic in\nsoftirq context.\n\n Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN NOPTI\n KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]\n RIP: 0010:icmp_unreach (net/ipv4/icmp.c:1085 net/ipv4/icmp.c:1143)\n Call Trace:\n \u003cIRQ\u003e\n icmp_rcv (net/ipv4/icmp.c:1527)\n ip_protocol_deliver_rcu (net/ipv4/ip_input.c:207)\n ip_local_deliver_finish (net/ipv4/ip_input.c:242)\n ip_local_deliver (net/ipv4/ip_input.c:262)\n ip_rcv (net/ipv4/ip_input.c:573)\n __netif_receive_skb_one_core (net/core/dev.c:6164)\n process_backlog (net/core/dev.c:6628)\n handle_softirqs (kernel/softirq.c:561)\n \u003c/IRQ\u003e\n\nAdd a NULL check before accessing icmp_strict_tag_validation. If the\nprotocol has no registered handler, return false since it cannot\nperform strict tag validation.",
"id": "GHSA-x3j5-9ghr-8cwm",
"modified": "2026-07-14T15:31:44Z",
"published": "2026-03-26T12:30:29Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23398"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1e4e2f5e48cec0cccaea9815fb9486c084ba41e2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1f9f2c6d4b2a613b7756fc5679c5116ba2ca0161"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/571d9d7b650f02d1e38c01128817868bceac9edd"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/614aefe56af8e13331e50220c936fc0689cf5675"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9647e99d2a617c355d2b378be0ff6d0e848fd579"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b61529c357f1ee4d64836eb142a542d2e7ad67ce"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d783fa413c702ff0f8f8bea63f862e28eeaf39e3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d938dd5a0ad780c891ea3bc94cae7405f11e618a"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.