# zebrad vulnerable to getblocks/getheaders locator CPU amplification via uncapped vector length

Advisory record · `GHSA-443g-gwgp-49x4`

- **Identifiers:** `GHSA-443g-gwgp-49x4` · `CVE-2026-104436`
- **State:** Confirmed
- **Severity:** CVSS 6.3 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-770](https://cwe.mitre.org/data/definitions/770.html)
- **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md)
- **Published:** 2 Jul 2026
- **Updated:** 3 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 2 Jul 2026, 19:34 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `zebrad` (crates.io): affected `<4.5.0`; fixed in `4.5.0`
- `zebra-chain` (crates.io): affected `<8.0.0`; fixed in `8.0.0`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> Zebrad versions up to and including 4.4.1 and zebra-chain versions before 8.0.0 accept block locator vectors of up to about 65,535 entries in getblocks and getheaders messages, far beyond the protocol limit of 101. A remote attacker with inbound P2P access can send oversized locators, which occupy blocking-pool threads with per-hash chain lookups and can degrade state reads under sustained multi-peer load. Upgrade zebrad to 4.5.0 and zebra-chain to 8.0.0. The source lists no workaround beyond existing backpressure.

Written 3 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 6.3 Medium, CVSS 4.0: `CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N`, from CNA (VulnCheck)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0027, the 19th percentile, on 15 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:24 UTC: First seen by agentprime
- 31 Oct 2026, 14:24 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-443g-gwgp-49x4)

## Sources

- [GitHub Advisory Database: GHSA-443g-gwgp-49x4](https://github.com/advisories/GHSA-443g-gwgp-49x4)
- [OSV: GHSA-443g-gwgp-49x4](https://osv.dev/vulnerability/GHSA-443g-gwgp-49x4)
- <https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-443g-gwgp-49x4>
- <https://github.com/ZcashFoundation/zebra/pull/10570>
- <https://github.com/ZcashFoundation/zebra/commit/8981a1b95d4807cad99e5bb3b94fc8bc723ac033>
- <https://github.com/ZcashFoundation/zebra>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-443g-gwgp-49x4>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-443g-gwgp-49x4/>. Everything for agents: <https://agentprime.io/llms.txt>.