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0xCERT Security Advisory 0xCERT-2026-0199
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Advisory-ID:  0xCERT-2026-0199
Severity:     Medium
Published:    2026-07-02T19:28:03.000Z
Updated:      2026-10-08T22:47:31.515Z
Chains:       n/a
URL:          https://www.0xcert.com/advisory/0xCERT-2026-0199

Title: zebrad has full node denial of service via non-ASCII LongPollId in getblocktemplate

Summary
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zebrad has full node denial of service via non-ASCII LongPollId in getblocktemplate. You are affected if: 1. You run zebrad up to and including v4.4.1. 2. Your zebrad.toml sets rpc.listenaddr to a TCP address (RPC server is enabled). 3. An attacker can authenticate to the RPC endpoint.

Details
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Summary
You are affected if: 1. You run zebrad up to and including v4.4.1. 2. Your zebrad.toml sets rpc.listenaddr to a TCP address (RPC server is enabled). 3. An attacker can authenticate to the RPC endpoint.

Affected
- - zebra-rpc (rust) <= 7.0.0 — fixed in 8.0.0
- - zebrad (rust) <= 4.4.1 — fixed in 4.5.0

Severity
Medium, as rated by the upstream advisory.

Recommended actions
- - Upgrade zebra-rpc to 8.0.0 or later
- - Upgrade zebrad to 4.5.0 or later

Source & attribution
This 0xCERT advisory summarises GHSA-qv2r-v3mx-f4pf / CVE-2026-52731 from the GitHub Advisory Database, credited upstream to sangsoo-osec, mpguerra, upbqdn: https://github.com/advisories/GHSA-qv2r-v3mx-f4pf. Details may change; refer to the original source for the authoritative record.

References
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- - https://github.com/advisories/GHSA-qv2r-v3mx-f4pf
- - CVE-2026-52731
- - https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-qv2r-v3mx-f4pf
- - https://github.com/ZcashFoundation/zebra/blob/d4cd662c716382f6397d2a730148025a1ca79fec/Cargo.toml#L305

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