icmp: fix NULL pointer dereference in icmp_tag_validation()
Summary
| CVE | CVE-2026-23398 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-03-26 11:16:19 UTC |
| Updated | 2026-03-30 13:26:50 UTC |
| Description | In 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: <IRQ> 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) </IRQ> 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. |
Risk And Classification
EPSS: 0.000320000 probability, percentile 0.091740000 (date 2026-04-01)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e 1f9f2c6d4b2a613b7756fc5679c5116ba2ca0161 git | Not specified |
| CNA | Linux | Linux | affected 8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e b61529c357f1ee4d64836eb142a542d2e7ad67ce git | Not specified |
| CNA | Linux | Linux | affected 8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e 9647e99d2a617c355d2b378be0ff6d0e848fd579 git | Not specified |
| CNA | Linux | Linux | affected 8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e d938dd5a0ad780c891ea3bc94cae7405f11e618a git | Not specified |
| CNA | Linux | Linux | affected 8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e 1e4e2f5e48cec0cccaea9815fb9486c084ba41e2 git | Not specified |
| CNA | Linux | Linux | affected 8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e 614aefe56af8e13331e50220c936fc0689cf5675 git | Not specified |
| CNA | Linux | Linux | affected 3.14 | Not specified |
| CNA | Linux | Linux | unaffected 3.14 semver | Not specified |
| CNA | Linux | Linux | unaffected 6.1.167 6.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.130 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.78 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.20 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.19.10 6.19.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.0-rc5 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/b61529c357f1ee4d64836eb142a542d2e7ad67ce | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/1e4e2f5e48cec0cccaea9815fb9486c084ba41e2 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/d938dd5a0ad780c891ea3bc94cae7405f11e618a | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/9647e99d2a617c355d2b378be0ff6d0e848fd579 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/614aefe56af8e13331e50220c936fc0689cf5675 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/1f9f2c6d4b2a613b7756fc5679c5116ba2ca0161 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.