icmp: fix NULL pointer dereference in icmp_tag_validation()
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: 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.
CVE-2026-23398
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-23398
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e",
"lessThan": "571d9d7b650f02d1e38c01128817868bceac9edd",
"versionType": "git"
},
{
"status": "affected",
"version": "8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e",
"lessThan": "d783fa413c702ff0f8f8bea63f862e28eeaf39e3",
"versionType": "git"
},
{
"status": "affected",
"version": "8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e",
"lessThan": "1f9f2c6d4b2a613b7756fc5679c5116ba2ca0161",
"versionType": "git"
},
{
"status": "affected",
"version": "8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e",
"lessThan": "b61529c357f1ee4d64836eb142a542d2e7ad67ce",
"versionType": "git"
},
{
"status": "affected",
"version": "8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e",
"lessThan": "9647e99d2a617c355d2b378be0ff6d0e848fd579",
"versionType": "git"
},
{
"status": "affected",
"version": "8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e",
"lessThan": "d938dd5a0ad780c891ea3bc94cae7405f11e618a",
"versionType": "git"
},
{
"status": "affected",
"version": "8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e",
"lessThan": "1e4e2f5e48cec0cccaea9815fb9486c084ba41e2",
"versionType": "git"
},
{
"status": "affected",
"version": "8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e",
"lessThan": "614aefe56af8e13331e50220c936fc0689cf5675",
"versionType": "git"
}
],
"programFiles": [
"net/ipv4/icmp.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "3.14"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "3.14",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.253",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.203",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.167",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.130",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.78",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.20",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "6.19.10",
"versionType": "semver",
"lessThanOrEqual": "6.19.*"
},
{
"status": "unaffected",
"version": "7.0",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/ipv4/icmp.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-23398
Source reference:
/cveMetadata/cveId
Publisher severity
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- Event
- #27250 · Revision 1
- Added to Heist Feed
- Publisher date