- Exploited
- No known exploitation
- Fix
- Fixed in 0.8.7, 0.9.0-beta.7.0
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 0.8.7, 0.9.0-beta.7.0.
- 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? →
- 10/100 · provisional
- 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
The bsv-rs package's Shamir backup recovery accepts a share with an x coordinate of 0. An attacker who supplies one such share to an application that recovers a backup from shares it did not produce can make the recovered private key a key of the attacker's choosing.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
KeyShares::from_backup_format (the Shamir backup share reader, public since 0.2.0, the crate's first release) accepted a share whose x coordinate is 0, and KeyShares::recover_private_key interpolates the shares at x = 0 to recover the key. At an x of 0 the interpolation answers that share's y value alone, so an attacker who supplies one share in that form — with the share's integrity tag ground to match the honest set's — chooses the recovered key outright. The non-canonical zero x = p works the same way, and a repeated x past the threshold window also passed.
An application that recovers a Shamir backup from shares it did not produce — a custodian's medium, a share pasted by hand, a set restored from another writer — could be handed the attacker's key as the recovered one. A set the crate's own writer produces never carries such a share; the door is the reader.
0.8.7 refuses such a set before interpolating (the 0.9 line's next prerelease carries the same refusal). Where upgrading is not possible, before recovering split each share on . into four fields, base58-decode the x field, and refuse the set if it decodes to zero (the one-character field 1, or a value at or above the field prime) or if two shares carry the same x.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure?/25Unknown. No advisory context yet
- Reach10/20Affects crates.io packages
- Severity?/10Unknown. No CVSS score or vendor rating
- No patch0/5No signal
What would change the score
- Would score about 65 if added to CISA KEV
- Would score about 60 if CISA's SSVC rates exploitation active
- Would score about 32 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 0.8.7, 0.9.0-beta.7.0.
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-2026-0501 (Shamir backup recovery accepts a share at x = 0, so a supplied share can substitute the recovered private key), 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-2026-0501 (entry last updated 2026-11-12):
Affected:
- crates.io package bsv-rs: from 0.0.0-0, fixed in 0.8.7; from 0.9.0-beta.1, fixed in 0.9.0-beta.7.0
Fixed versions: 0.8.7, 0.9.0-beta.7.0.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: RUSTSEC-2026-0501 is not listed as of cve.now's last read.
This KEV status is for RUSTSEC-2026-0501 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-2026-0501.html
- https://github.com/Calhooon/bsv-rs/issues/854
- https://crates.io/crates/bsv-rs
- https://github.com/Calhooon/bsv-rs/blob/v0.8.7/CHANGELOG.md
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-2026-0501
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-2026-0501"}.Timeline
- First seen by cve.now
- Advisory published
Affected versions
- bsv-rscrates.io
From 0.0.0-0 · fixed in 0.8.7; From 0.9.0-beta.1 · fixed in 0.9.0-beta.7.0
Evidence 4
Other links · 4
- Advisory
- Report
- Repository
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about RUSTSEC-2026-0501
Is RUSTSEC-2026-0501 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-2026-0501?
bsv-rs (crates.io): from 0.0.0-0 before 0.8.7; from 0.9.0-beta.1 before 0.9.0-beta.7.0.Source: cve.now feed data
How do I fix RUSTSEC-2026-0501?
Upgrade to a fixed version: 0.8.7, 0.9.0-beta.7.0.Source: cve.now feed data