Answer in brief
CVE-2026-23381 records a Medium severity (CVSS 5.5) vulnerability in net: bridge: fix nd_tbl NULL dereference when IPv6 is disabled. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic) and additional mapped packages. 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 5.5. 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), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=ed842faeb2bd49256f00485402f3113205f91d30 <a9d712ccfeef737c0e700a4b5b98f310e07b6b60 || >=ed842faeb2bd49256f00485402f3113205f91d30 <a5c56e65b685360dd3f2278aeff8c21061feb665 || >=ed842faeb2bd49256f00485402f3113205f91d30 <7a894eb5de246d79f13105c55a67381039a24d44 || >=ed842faeb2bd49256f00485402f3113205f91d30 <a12cdaa3375f0bd3c8f4e564be7c143529abfe5b || >=ed842faeb2bd49256f00485402f3113205f91d30 <aa73deb3b6b730ec280d45b3f423bfa9e17bc122 || >=ed842faeb2bd49256f00485402f3113205f91d30 <33dec6f10777d5a8f71c0a200f690da5ae3c2e55 || >=ed842faeb2bd49256f00485402f3113205f91d30 <20ef5c25422f97dd09d751e5ae6c18406cdc78e6 || >=ed842faeb2bd49256f00485402f3113205f91d30 <e5e890630533bdc15b26a34bb8e7ef539bdf1322 | a9d712ccfeef737c0e700a4b5b98f310e07b6b60, a5c56e65b685360dd3f2278aeff8c21061feb665, 7a894eb5de246d79f13105c55a67381039a24d44, a12cdaa3375f0bd3c8f4e564be7c143529abfe5b, aa73deb3b6b730ec280d45b3f423bfa9e17bc122, 33dec6f10777d5a8f71c0a200f690da5ae3c2e55, 20ef5c25422f97dd09d751e5ae6c18406cdc78e6, e5e890630533bdc15b26a34bb8e7ef539bdf1322 |
| Linux/Linuxgeneric | 4.15 | Not reported |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
Published upstream
Mar 25, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 8, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 14, 2026
In the Linux kernel, the following vulnerability has been resolved: net: bridge: fix nd_tbl NULL dereference when IPv6 is disabled When booting with the 'ipv6.disable=1' parameter, the nd_tbl is never initialized because inet6_init() exits before ndisc_init() is called which initializes it. Then, if neigh_suppress is enabled and an ICMPv6 Neighbor Discovery packet reaches the bridge, br_do_suppress_nd() will dereference ipv6_stub->nd_tbl which is NULL, passing it to neigh_lookup(). This causes a kernel NULL pointer dereference. BUG: kernel NULL pointer dereference, address: 0000000000000268 Oops: 0000 [#1] PREEMPT SMP NOPTI [...] RIP: 0010:neigh_lookup+0x16/0xe0 [...] Call Trace: <IRQ> ? neigh_lookup+0x16/0xe0 br_do_suppress_nd+0x160/0x290 [bridge] br_handle_frame_finish+0x500/0x620 [bridge] br_handle_frame+0x353/0x440 [bridge] __netif_receive_skb_core.constprop.0+0x298/0x1110 __netif_receive_skb_one_core+0x3d/0xa0 process_backlog+0xa0/0x140 __napi_poll+0x2c/0x170 net_rx_action+0x2c4/0x3a0 handle_softirqs+0xd0/0x270 do_softirq+0x3f/0x60 Fix this by replacing IS_ENABLED(IPV6) call with ipv6_mod_enabled() in the callers. This is in essence disabling NS/NA suppression when IPv6 is disabled.
Quoted source text, attributed separately from HOL analysis.