NVD / CVE Program· CNA zephyr

CVE-2026-10639: Use-after-free reading `net_pkt_iface()` of a sent ICMPv4 echo-reply packet in `icmpv4_handle_echo_request()`

Noroxi assessment

Priority: Monitor (action score 19/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.23% (FIRST EPSS).
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
Fixed version: zephyrproject zephyr 4.3.1, 4.4.1.

Low priority for now. Upgrade to zephyrproject zephyr 4.3.1, 4.4.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In Zephyr's native IPv4 stack, icmpv4_handle_echo_request() in subsys/net/ip/icmpv4.c builds an echo-reply packet (reply), hands it to net_try_send_data(), and then, on success, calls net_stats_update_icmp_sent(net_pkt_iface(reply)). net_try_send_data() transfers ownership of reply to the TX path (net_if_try_queue_tx -> net_if_tx -> L2/driver send, or the asynchronous net_if_tx_thread), which can unref it to refcount 0 and return the struct net_pkt to its slab (net_pkt_unref -> k_mem_slab_free) before the stats line runs. net_core.c documents this exact contract ('the pkt might contain garbage already ... do not use pkt after that call'). The post-send net_pkt_iface(reply) therefore reads reply->iface out of a freed (and possibly already reallocated) net_pkt, a use-after-free read; with CONFIG_NET_STATISTICS_PER_INTERFACE the stats macro additionally increments a counter through that value, i.e. a dereference/write through a stale or recycled-slot pointer. The path is reached unauthenticated by any remote host that pings the device (net_icmpv4_input -> net_icmp_call_ipv4_handlers -> icmpv4_handle_echo_request) and is gated on CONFIG_NET_STATISTICS_ICMP. Impact is a probabilistic read of recycled packet memory plus a possible wild-pointer write under a timing race, leading most likely to corrupted interface statistics or a remotely triggerable crash (DoS). The defect was introduced in 2019 (v1.14) and is present through v4.4.0. The companion change in net_icmpv4_send_error() is not a use-after-free because it reads net_pkt_iface(orig), the caller-owned received packet, which stays alive across the send. The fix caches the interface pointer from the live received packet before sending and uses it for the post-send stats updates.

MediumCVSS 4.8 · v3.1—No exploit Fix available

Published: Jun 16, 2026
Updated: Nov 4, 2026
EPSS: 0.2% · 14th percentile
CWE: CWE-416

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 19 / 40 · 4.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.2%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: 4.8
CNA · zephyr: 4.8; agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Running WordPress? Scan your site free with WP Lens

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

We use this product, ask for help

Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
zephyrproject	zephyr	cpe:2.3:o:zephyrproject:zephyr

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

zephyrproject zephyr1.14.0 and later · before 4.5.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (zephyr). Independent of NVD's CPE analysis and usually ahead of it.

zephyrproject zephyr
- 4.2.0 and later · before 4.3.1affected · semver
- 4.4.0 and later · before 4.4.1affected · semver

Same product

zephyrproject: all records

Other highest-scoring records for the same primary product.

CVE-2023-4260Potential off-by-one buffer overflow vulnerability in the Zephyr FS subsystem
40Plan
CVE-2021-3625Buffer overflow in Zephyr USB DFU DNLOAD
40Plan
CVE-2020-10071Insufficient publish message length validation in MQTT
40Plan

Published before and after this one in the same product

← EarlierCVE-2026-10637Jun 16, 2026 · Use-after-free of `net_pkt` in IPv6 MLD send path triggerable by a link-local MLD Query
28Monitor
← EarlierCVE-2026-10638Jun 16, 2026 · Use-after-free in Zephyr ICMPv6 RX path when updating statistics after sending an echo reply or error
30Monitor
Later →CVE-2026-10640Jun 16, 2026 · Use-after-free reading `net_pkt` `iface` after send in IPv6 Neighbor Discovery (`ipv6_nbr.c`)
28Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
zephyrproject zephyr	4.3.1	Vendor (CNA)
zephyrproject zephyr	4.4.1	Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

zephyrproject-rtos/zephyrcommit 86e2166

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2026-1236659 days apartUse-after-free freeing an armed dynamically-allocated k_timer in Zephyr userspace object disposal
35Monitor
CVE-2026-85035140 days apartUse-after-free via dynamically allocated message queue retained by the CAN RX filter
35Monitor
CVE-2026-1066726 days apartSMP use-after-free in Zephyr `CONFIG_USERSPACE` dynamic kernel-object tracking, reachable from unprivileged user threads
31Monitor
CVE-2026-79979129 days apartStale TLB entries after demand-paging page-out let arm64 user threads access reused physical frames
31Monitor
CVE-2026-106380 days apartUse-after-free in Zephyr ICMPv6 RX path when updating statistics after sending an echo reply or error
30Monitor
CVE-2026-1068545 days apartUse-after-free of GATT subscribe params in Bluetooth host CCC-write response handler
30Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
No user action is required.
Special conditions such as timing or configuration are required.

If successful

Confidentiality: none
Integrity: low · data or configuration can be modified
Availability: low · the service can be disrupted

Attack vector: Network
Attack complexity: High
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: None
Integrity impact: Low
Availability impact: Low

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

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

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

Fix✗ → ✓Sep 28, 2026, 10:11 PM UTC

For records you follow, these changes also arrive as notifications. →

References

github.com/zephyrproject-rtos/zephyr/commit/86e21665d4641f304dc3895bfb03b8f89db83291

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records