- Exploited
- No known exploitation
- Fix
- Fixed in 0.8.6, 0.9.0-beta.7.0
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 0.8.6, 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 `Signature::from_der` parses DER-encoded ECDSA signatures too leniently, accepting trailing bytes, wrong sequence lengths, and unneeded leading zeros, and several verification functions in the package accept these alternate forms. An attacker who has one valid signature from a key holder can produce other byte strings that verify as that same signature over the same data, which affects only applications that compare, hash, or store the signature bytes.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
Signature::from_der read a DER-encoded ECDSA signature leniently. It read as the signature: the signature followed by other bytes; a sequence length shorter than its contents, or longer with bytes after them (a length byte with its high bit set among them); and an R or S preceded by a zero byte it did not need. It read a lone-zero R or S as zero.
messages::verify, compat::bsm::verify_message_der, auth::Certificate::verify, auth::VerifiableCertificate::verify, wallet::ProtoWallet::verify_signature and kvstore::KVStoreInterpreter::verify_signature read through it, and each verified such a form of a valid signature. Given one signature a key holder made, anyone could produce other byte strings that verify as that signature over the same data. No form verifies over other data: an application that acts on the verdict alone is not affected; one that compares, hashes or stores a signature's bytes is.
0.8.6 refuses each form as Error::InvalidSignature. A signature's bytes are still not unique after the patch: the same signature with S replaced by n - S verifies, so an application that keys on the bytes also requires Signature::is_low_s().
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: 0.8.6, 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-2026-0499 (Signature::from_der reads a signature with bytes after it, a wrong sequence length or an unneeded zero as the signature), 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-2026-0499 (entry last updated 2026-11-12):
Affected:
- crates.io package bsv-rs: from 0.0.0-0, fixed in 0.8.6; from 0.9.0-beta.1, fixed in 0.9.0-beta.7.0
Fixed versions: 0.8.6, 0.9.0-beta.7.0.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: RUSTSEC-2026-0499 is not listed as of cve.now's last read.
This KEV status is for RUSTSEC-2026-0499 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-2026-0499.html
- https://github.com/Calhooon/bsv-rs/issues/842
- https://crates.io/crates/bsv-rs
- https://github.com/Calhooon/bsv-rs/blob/v0.8.6/CHANGELOG.md
- https://github.com/Calhooon/bsv-rs/pull/846
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-2026-0499
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-2026-0499"}.Timeline
- Advisory published1 day
- Record last updated
- First seen by cve.now
Affected versions
- bsv-rscrates.io
From 0.0.0-0 · fixed in 0.8.6; From 0.9.0-beta.1 · fixed in 0.9.0-beta.7.0
Evidence 5
Other links · 5
- Advisory
- Report
- Repository
- Repository
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about RUSTSEC-2026-0499
Is RUSTSEC-2026-0499 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-2026-0499?
bsv-rs (crates.io): from 0.0.0-0 before 0.8.6; from 0.9.0-beta.1 before 0.9.0-beta.7.0.Source: cve.now feed data
How do I fix RUSTSEC-2026-0499?
Upgrade to a fixed version: 0.8.6, 0.9.0-beta.7.0.Source: cve.now feed data