# CVE-2026-12630: 6LoWPAN IPHC uncompression out-of-bounds read on reserved destination addressing mode

> An unauthenticated attacker can cause a denial of service in Zephyr RTOS by sending a crafted 6LoWPAN 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:** 17 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** GHSA-45c8-pmgj-6jrc

## What is CVE-2026-12630?

CVE-2026-12630 is a medium-severity memory corruption vulnerability in zephyrproject zephyr, published on 17 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Zephyr's 6LoWPAN IP Header Compression (IPHC) uncompression code contains an out-of-bounds read in get_ihpc_inlined_size() (subsys/net/ip/6lo.c). The destination inline size is looked up in da_inline_size_table, which has 13 entries, using an index built from the M, DAC and DAM bits of the received IPHC dispatch word (iphc & NET_6LO_IPHC_DA_MASK, a 4-bit value of 0-15). The reserved combinations 13, 14 and 15 are not bounds-checked and read past the end of the table.

The iphc word is taken directly from the received frame, and get_ihpc_inlined_size() is reached on every inbound 6LoWPAN frame via net_6lo_uncompress() from the 802.15.4 receive path (subsys/net/l2/ieee802154/ieee802154_6lo.c and ieee802154_6lo_fragment.c). An unauthenticated attacker on the radio/adjacent link can therefore craft a frame whose destination addressing-mode nibble selects an out-of-range index, with no privileges or user interaction.

The out-of-bounds value becomes the computed inline_size, which then drives header reconstruction before the buffer-length check: it is used to dereference *(pkt->buffer->data + sizeof(iphc) + inline_size) and to compute a size_t diff that can underflow, leading to a further out-of-bounds read of the packet buffer and malformed uncompression. The practical impact is a radio-triggerable out-of-bounds read / denial-of-service on the receiver; the leaked byte is not returned to the attacker. The fix rejects any destination index beyond the table, aborting processing of the malformed frame.

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

## Which versions are affected by CVE-2026-12630?


## How do I fix CVE-2026-12630?

No fix has been published for CVE-2026-12630 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-12630 being exploited?

There is no known exploitation of CVE-2026-12630 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-12630 and fix it if it is affected.

What it is: CVE-2026-12630 is a medium-severity memory corruption vulnerability in zephyrproject zephyr, published on 17 Aug 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-2026-12630 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-2026-12630/ (Markdown: https://insights.sbomify.com/CVE-2026-12630/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-12630
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-12630
- OSV: https://osv.dev/vulnerability/CVE-2026-12630

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-12630/
Summaries are generated and may contain mistakes; the official description above is the record.