# CVE-2026-16514: Out-of-bounds read in gPTP Announce path-trace validation via unvalidated stepsRemoved

> An unauthenticated attacker on the same Ethernet segment can cause a denial of service by sending a crafted gPTP Announce frame that triggers an out-of-bounds read.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 18 Sep 2026
- **Updated:** 18 Sep 2026
- **Also known as:** GHSA-mgxg-89rr-6855

## What is CVE-2026-16514?

CVE-2026-16514 is a medium-severity denial of service vulnerability in zephyrproject zephyr, published on 18 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

gptp_mi_qualify_announce() in subsys/net/l2/ethernet/gptp/gptp_mi.c walks the Path Trace TLV of a received IEEE 802.1AS Announce message, comparing each clock identity against the local one. The loop bound was taken solely from the attacker-controlled wire field announce->steps_removed (accepted up to 254), never from announce->tlv.len, which is the field that states how many identities the TLV actually carries. Because path_sequence is the flexible member of the wire TLV (struct gptp_path_trace_tlv) and GPTP_ANNOUNCE() yields a raw pointer into the received packet buffer, the memcmp() inside the loop can address memory well past the end of the received frame.

The stack's only length validation, GPTP_ANNOUNCE_CHECK_LEN(), requires the received gPTP payload to be exactly 68 + tlv.len bytes — so it does not constrain the loop, it guarantees the data is absent. An unauthenticated attacker on the same Ethernet segment can send a single Announce frame declaring tlv.len = 0 with steps_removed = 254; the frame passes the length check and reception path (net_gptp_recv() → gptp_handle_msg() → gptp_mi_qualify_announce()), which performs no authentication, and the loop then reads 255 entries of 8 bytes each — about 2 KB — beyond the end of the network buffer.

The impact is an out-of-bounds read. The bytes read are only used as a memcmp() operand and are never returned to the attacker, so there is no meaningful information disclosure; the practical risk is that the overread crosses a network buffer pool boundary into unmapped or MPU-protected memory and faults the networking RX thread, causing a denial of service. Exposure is limited to builds that enable the opt-in, experimental CONFIG_NET_GPTP (TSN/AVB deployments) and to attackers with layer-2 adjacency, since gPTP frames are sent to a link-local multicast address and are not routed.

The fix computes the true entry count as tlv.len / GPTP_CLOCK_ID_LEN and rejects the announce when steps_removed + 1 exceeds it, so the loop can no longer run past the data the packet-length check proved present.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-16514?


## How do I fix CVE-2026-16514?

No fix has been published for CVE-2026-16514 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-16514 being exploited?

There is no known exploitation of CVE-2026-16514 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-16514 and fix it if it is affected.

What it is: CVE-2026-16514 is a medium-severity denial of service vulnerability in zephyrproject zephyr, published on 18 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-16514 in the wild and no public exploit code.

Affected product: zephyrproject zephyr. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-16514/ (Markdown: https://insights.sbomify.com/CVE-2026-16514/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-16514
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-16514
- OSV: https://osv.dev/vulnerability/CVE-2026-16514

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-16514/
Summaries are generated and may contain mistakes; the official description above is the record.