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VulnerabilityPublished Updated

CVE-2026-10637: zephyrproject zephyr · Use After Free

Affects zephyrproject zephyrSource CVE Database V5

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Not known to be exploited · CVSS 5.9 Medium : upgrade to 4.4.1 or 4.3.1 when convenient.

Data as of 30 Oct 2026, 20:25 UTC

CVSS 3.1 base score
5.9Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 22% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.4.1, 4.3.1
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 16 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade zephyrproject zephyr to 4.4.1 or 4.3.1.

Affected software

ProductAffectedFixed in
zephyrprojectzephyrAffected
  • >=4.4.0 <4.4.1
Fixed in
  • 4.4.1
zephyrprojectzephyrAffected
  • >=1.12.0 <4.3.1
Fixed in
  • 4.3.1
GitHubzephyrpkg:github/zephyrOther threatsAffected
  • >=1.12.0 <4.3.1
  • >=4.4.0 <4.4.1
Fixed in
  • 4.3.1
  • 4.4.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, network administrators should consider limiting exposure to untrusted local link traffic that can send MLDv2 General Queries if feasible.

Description

subsys/net/ip/ipv6_mld.c:mld_send() read the packet interface via net_pkt_iface(pkt) after net_send_data(pkt) returned successfully. Per the network stack's ownership contract (include/zephyr/net/net_core.h, and the explicit warning in subsys/net/ip/net_core.c:453-460 'do not use pkt after that call'), a successful send transfers ownership of the net_pkt and the L2 driver frees it (e.g. ethernet_send() unrefs the packet on success, subsys/net/l2/ethernet/ethernet.c:790), returning it to its k_mem_slab. The subsequent net_pkt_iface(pkt) is therefore a read of a freed object; the recovered interface pointer is then dereferenced and incremented by the per-interface statistics path (net_stats.h UPDATE_STAT/SET_STAT) when CONFIG_NET_STATISTICS_PER_INTERFACE is enabled. If the freed slot is concurrently reallocated, pkt->iface may read back as NULL (NULL-pointer dereference / crash) or as a stale/garbage pointer (stray increment write / memory corruption). The path is reachable remotely on the local link without authentication: handle_mld_query() (registered for NET_ICMPV6_MLD_QUERY) responds to a valid MLDv2 General Query (unspecified multicast address, hop limit 1) by calling send_mld_report() -> mld_send(). The result is a remotely triggerable denial of service of the networking stack, with a narrow possibility of memory corruption. The fix caches the interface in a local before sending and no longer touches the packet after net_send_data(). The IPv4/IGMP sibling (igmp_send) already used the corrected pattern.

References

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