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CVE-2026-10638

MEDIUM 5.9

Published 2026-06-16 · Last modified 2026-07-17

subsys/net/ip/icmpv6.c reads the network interface from a net_pkt after that packet has been handed to net_try_send_data(). In icmpv6_handle_echo_request() and net_icmpv6_send_error(), the post-send statistics update calls net_pkt_iface(reply)/net_pkt_iface(pkt) on the just-sent packet. The send path (net_try_send_data -> net_if_tx) unreferences and may free the packet back to its memory slab before returning — synchronously in the RX thread when no TX queue is configured (CONFIG_NET_TC_TX_COUNT == 0), and asynchronously the driver/L2 may already have freed it otherwise. net_pkt_iface() therefore dereferences a freed (and possibly reused) net_pkt; with CONFIG_NET_STATISTICS_PER_INTERFACE the stale iface pointer is further dereferenced and written through (iface->stats.icmp.sent++), turning the use-after-free read into a write through an attacker-influenceable pointer. The core stack already documents this hazard in net_core.c ("do not use pkt after that call") and caches iface before sending; the ICMPv6 callers did not. An unauthenticated remote attacker triggers the flaw simply by sending an ICMPv6 Echo Request (ping) or an IPv6 packet that elicits an ICMPv6 error (unknown next header, fragment reassembly timeout, destination unreachable), leading to denial of service via crash and potential memory corruption. Affected: Zephyr networking with CONFIG_NET_NATIVE_IPV6, roughly v4.2.0 through v4.4.0. The fix caches the interface pointer before sending and uses it for all statistics updates; the sibling commit 86e21665d46 fixes the identical bug in ICMPv4.

NO EXPLOITATION SIGNALS

No known exploitation, public exploit, or elevated probability at this time. Track for changes.

Exploitation likelihood

0.4%chance of exploitation in 30 days · 28th percentile

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

5.9CVSS 3.1 · MEDIUM

  • ConfidentialityNone
  • IntegrityNone
  • AvailabilityHigh

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ✓User interaction: No user interaction needed
  • ⚠Complexity: Needs a race window or specific setup

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept & exploit code

Test against your own equipment

curl -s https://vulnpedia.com/cve/CVE-2026-10638/poc.jsonMachine-readable PoC index for this CVE (for automation).

Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-10638/poc.json

Affected

Vendors Zephyrproject

Products Zephyr

Weakness (CWE)

  • CWE-416: use-after-free

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Known Affected Software Configurations

VendorProductVersion range
ZephyrprojectZephyr≥ 4.2.0 and < 4.5.0

All CVSS metrics

  • MEDIUM 5.9 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
  • MEDIUM 5.9 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
  • HIGH 7.5 v3.1 · NVD Primary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

Patches & mitigations

Technical & other

Sources: NVD · CVE.org · EPSS