# CVE-2026-52731: ZEBRA: Full node denial of service via non-ASCII LongPollId in getblocktemplate

> An authenticated attacker can crash the Zebra Zcash node by sending a malformed RPC request with multi-byte characters in the LongPollId.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Aug 2026
- **Updated:** 18 Aug 2026
- **Also known as:** GHSA-qv2r-v3mx-f4pf

## What is CVE-2026-52731?

CVE-2026-52731 is a medium-severity denial of service vulnerability in ZcashFoundation zebra, published on 18 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

ZEBRA is a Zcash node written entirely in Rust. Prior to 4.5.0, an attacker authenticated to an enabled Zebra RPC endpoint can terminate zebrad by supplying a getblocktemplate LongPollId containing multi-byte UTF-8 characters. In zebra-rpc/src/methods/types/long_poll.rs, LongPollId::from_str originally checked the input byte length and then sliced fixed byte ranges to parse encoded fields. A slice boundary can land inside a multi-byte character and trigger Rust's byte index is not a char boundary panic. Zebra release builds use panic equals abort, so one malformed authenticated RPC request terminates the entire node process and can be repeated after restart. This issue is fixed in version 4.5.0.

Weakness: CWE-248 (Uncaught Exception)

## Which versions are affected by CVE-2026-52731?

4 open source packages ship an affected version, including zebra-rpc and zebrad.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `zebra-rpc` | crates.io | All versions | 8.0.0 |
| `zebra-rpc` | crates.io | All versions | 8.0.0 |
| `zebrad` | crates.io | All versions | 4.5.0 |
| `zebrad` | crates.io | All versions | 4.5.0 |

## How do I fix CVE-2026-52731?

Upgrade zebra-rpc to 8.0.0 or later.

## Is CVE-2026-52731 being exploited?

There is no known exploitation of CVE-2026-52731 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-52731 and fix it if it is affected.

What it is: CVE-2026-52731 is a medium-severity denial of service vulnerability in ZcashFoundation zebra, published on 18 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-52731 in the wild and no public exploit code.

Affected packages and fixed versions:
- zebra-rpc (crates.io): affected all versions; fixed in 8.0.0
- zebra-rpc (crates.io): affected all versions; fixed in 8.0.0
- zebrad (crates.io): affected all versions; fixed in 4.5.0
- zebrad (crates.io): affected all versions; fixed in 4.5.0

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-2026-52731/ (Markdown: https://insights.sbomify.com/CVE-2026-52731/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-52731
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-52731
- OSV: https://osv.dev/vulnerability/CVE-2026-52731

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-52731/
Summaries are generated and may contain mistakes; the official description above is the record.