RUSTSEC-2026-0227: NIP-44 v2 decryption permits resource exhaustion

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-44 decryption entry point Base64-decoded the complete attacker-controlled payload before determining its version or enforcing any size limit. For v2 payloads, the decoded buffer was then authenticated with HMAC even when it was much larger than the maximum payload supported by the crate's current v2 codec.

A malicious relay or event author could deliver an oversized value to an application that decrypts NIP-44 content. The value caused memory allocation and Base64 and HMAC work proportional to its size before authentication failed; knowledge of the conversation key was not required to consume those initial resources. Repeated payloads could exhaust memory or CPU and make the receiving application unavailable. The issue does not disclose plaintext or key material and does not bypass message authentication.

Decryption now reads only the encoded version prefix first, derives the bound from the largest payload the current v2 encoder can emit, and rejects oversized encoded and decoded payloads before full allocation or HMAC processing. The limit remains in the v2 implementation so a future codec with a different length format can define its own bound.

References

• Package: crates.io/crates/nostr
• Advisory: rustsec.org/advisories/RUSTSEC-2026-0227.html
• Web: github.com/nostrdevkit/nostr/commit/89dc1a77eaa774174588c5a38b6324c502948830

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 MediumRUSTSEC-2026-0228 · 2026-08-01NIP-04 parsing amplifies malformed ciphertext memory use
• 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