- Exploited
- No known exploitation
- Fix
- Fixed in 0.50.1
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 0.50.1.
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 12/100 · provisional
- The share of the registry's downloads of each affected package in the window that were versions inside the affected ranges. Downloads, not users or installs: CI runs and mirrors inflate the counts.
- 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
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
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.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original 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.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure?/25Unknown. No advisory context yet
- Reach12/20libp2p-gossipsub: 106K downloads a week
- Severity?/10Unknown. No CVSS score or vendor rating
- No patch0/5No signal
What would change the score
- Would score about 67 if added to CISA KEV
- Would score about 62 if CISA's SSVC rates exploitation active
- Would score about 34 if advisories confirm default setups are exposed
Impact
- Widely used
libp2p-gossipsub has 106k weekly downloads.Source: crates.io
What to do
Upgrade to a fixed version: 0.50.1.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
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"}.Timeline
- Advisory published25 days
- Record last updated
Affected versions
- libp2p-gossipsubcrates.io
From 0.0.0-0 · 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.
Evidence 4
Other links · 4
- Advisory
- Repository
- Repository
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about RUSTSEC-2026-0534
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: cve.now feed data
Which versions are affected by RUSTSEC-2026-0534?
libp2p-gossipsub (crates.io): from 0.0.0-0 before 0.50.1.Source: cve.now feed data
How do I fix RUSTSEC-2026-0534?
Upgrade to a fixed version: 0.50.1.Source: cve.now feed data