RUSTSEC-2026-0228: NIP-04 parsing amplifies malformed ciphertext memory use

What to do

1. See which version you have: cargo tree -i nostr (it also shows which of your dependencies pulls it in).
2. Update within your version requirement: cargo update -p nostr. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for example nostr = "0.44.7") or update the dependency that pulls it in.
3. Check again with cargo audit, or paste your Cargo.lock into our Cargo.toml checker.

Details from the advisory

The NIP-04 decryption parser split attacker-controlled content on every ?iv= separator and collected all resulting segments before checking that the message had the expected two parts. It also Base64-decoded the complete IV text before checking that it represented the required 16-byte AES-CBC IV.

A malicious sender could include a large number of separators or an oversized IV in an encrypted direct message. Applications that attempted to decrypt the message performed avoidable allocations proportional to the malformed input, with additional allocation amplification from the segment vector and Base64 output. This can consume memory and CPU in clients processing messages received through a relay. It does not weaken NIP-04 encryption or reveal plaintext or key material.

The parser now uses a single bounded split, rejects additional separators, and validates the 24-byte encoded IV length before Base64 decoding. Malformed inputs are returned as errors without allocating for every separator or decoding an arbitrarily large IV.

References

• Package: crates.io/crates/nostr
• Advisory: rustsec.org/advisories/RUSTSEC-2026-0228.html
• Web: github.com/nostrdevkit/nostr/commit/25e4e9ce66a533d9d7f5071f6c1dae992476cf83

From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.

Other advisories for nostr

• Vulnerability HighRUSTSEC-2026-0216 · 2026-07-25Remote Denial of Service via malformed NIP‑44 v2 payload
• Vulnerability HighRUSTSEC-2026-0219 · 2026-07-26Remote Denial of Service via malformed NIP-04 IV
• Vulnerability MediumRUSTSEC-2026-0225 · 2026-08-01Debug output exposes NIP-46 and NIP-60 credentials
• Vulnerability HighRUSTSEC-2026-0226 · 2026-08-01Wallet event parsers accept unauthenticated events
• Vulnerability HighRUSTSEC-2026-0227 · 2026-08-01NIP-44 v2 decryption permits resource exhaustion
• Vulnerability HighRUSTSEC-2026-0229 · 2026-08-01NIP-98 authorization parsing permits resource exhaustion
• Vulnerability HighRUSTSEC-2026-0230 · 2026-08-01Empty NIP-50 search filters can panic

Full security history of nostr