# CVE-2026-53920: odhcpd DHCPv6 Short IA_NA/IA_PD Body Stack Disclosure


- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 23 Oct 2026
- **Updated:** 23 Oct 2026
- **Also known as:** GHSA-p769-5v73-pc4f

## What is CVE-2026-53920?

CVE-2026-53920 is a high-severity vulnerability in openwrt odhcpd, published on 23 Oct 2026. 

### Official description

odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. From version 17.01.0 to before version 25.12.3, odhcpd's DHCPv6 IA parser accepts an IA_NA or IA_PD option whose body is shorter than struct dhcpv6_ia_hdr, casts the option header to that full structure, and reads ia->iaid before proving that the IA body contains the IAID field. If an unauthenticated network-adjacent client places a zero-length or otherwise short IA option at the end of odhcpd's 8192-byte receive stack buffer, the IAID read crosses from data_buf into adjacent stack memory. The disclosed bytes are then reflected in the DHCPv6 reply IAID; prior ARM validation showed data_buf[8192:8196] disclosing the saved stack canary, and wider stack scans can leak ASLR-useful stack/process contents. This issue has been patched in version 25.12.3.

Weakness: CWE-201 (Insertion of Sensitive Information Into Sent Data), CWE-126 (Buffer Over-read), CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-53920?


## How do I fix CVE-2026-53920?

No fix has been published for CVE-2026-53920 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-53920 being exploited?

There is no known exploitation of CVE-2026-53920 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53920 and fix it if it is affected.

What it is: CVE-2026-53920 is a high-severity vulnerability in openwrt odhcpd, published on 23 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-53920 in the wild and no public exploit code.

Affected product: openwrt odhcpd. 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-2026-53920/ (Markdown: https://insights.sbomify.com/CVE-2026-53920/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53920
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53920
- OSV: https://osv.dev/vulnerability/CVE-2026-53920

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53920/
Summaries are generated and may contain mistakes; the official description above is the record.