# CVE-2026-27816: EVerest's ISO15118 update_energy_transfer_modes overflow can corrupt EVSE state

> Attackers can corrupt EVSE state or crash the process via oversized MQTT payloads due to missing bounds checking in EVerest's ISO15118 implementation.

- **Severity:** Medium 5.5 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P`)
- **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:** 26 Mar 2026
- **Updated:** 26 Mar 2026
- **Also known as:** GHSA-gq54-j8f4-xj8c

## What is CVE-2026-27816?

CVE-2026-27816 is a medium-severity memory corruption vulnerability in everest-core, published on 26 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

EVerest is an EV charging software stack. Prior to versions to 2026.02.0, ISO15118_chargerImpl::handle_update_energy_transfer_modes copies a variable-length list into a fixed-size array of length 6 without bounds checking. With schema validation disabled by default, oversized MQTT Cmd payloads can trigger out-of-bounds writes and corrupt adjacent EVSE state or crash the process. Version 2026.02.0 contains a patch.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-27816?

It affects 1 product.


Products: Linuxfoundation Everest.

## How do I fix CVE-2026-27816?

No fix has been published for CVE-2026-27816 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-27816 being exploited?

There is no known exploitation of CVE-2026-27816 in the wild and no public exploit code.

## Other vulnerabilities in everest-core

- [CVE-2026-22790](https://insights.sbomify.com/CVE-2026-22790/): EVerest's unchecked SLAC payload length causes stack overflow in HomeplugMessage::setup_payload (high 8.8)
- [CVE-2026-22593](https://insights.sbomify.com/CVE-2026-22593/): EVerest has off-by-one stack buffer overflow in IsoMux certificate filename parsing (high 8.4)
- [CVE-2026-23995](https://insights.sbomify.com/CVE-2026-23995/): EVerest has stack buffer overflow in ifreq.ifr_name when interface name exceeds IFNAMSIZ (high 8.4)
- [CVE-2025-68137](https://insights.sbomify.com/CVE-2025-68137/): EVerest's Integer Overflow and Signed to Unsigned conversion lead to either stack buffer overflow or infinite loop (high 8.4)
- [CVE-2026-33009](https://insights.sbomify.com/CVE-2026-33009/): EVerest: MQTT Switch-Phases Command Data Race Causing Charger State Corruptio (high 8.2)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-27816 and fix it if it is affected.

What it is: CVE-2026-27816 is a medium-severity memory corruption vulnerability in everest-core, published on 26 Mar 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-2026-27816 in the wild and no public exploit code.

Affected product: everest-core. 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-2026-27816/ (Markdown: https://insights.sbomify.com/CVE-2026-27816/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-27816
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-27816
- OSV: https://osv.dev/vulnerability/CVE-2026-27816

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-27816/
Summaries are generated and may contain mistakes; the official description above is the record.