Vulnerability HighRUSTSEC-2021-0056 · openssl-src
RUSTSEC-2021-0056: CA certificate check bypass with X509_V_FLAG_X509_STRICT
Short answerA security vulnerability in the openssl-src crate: CA certificate check bypass with X509_V_FLAG_X509_STRICT. High severity (CVSS 7.4). Fixed in 111.15.0: update to a fixed version.
| Crate | openssl-src |
|---|---|
| Type | Vulnerability (crypto-failure) |
| Affected versions | From 111.11.0 before 111.15.0. |
| Fixed in | 111.15.0 |
| Severity | High, CVSS 7.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N |
| Published | 2021-05-01 |
| Last changed | 2024-12-16 |
| Also known as | BIT-node-2021-3450, BIT-node-min-2021-3450, CVE-2021-3450, GHSA-8hfj-xrj2-pm22 |
What to do
- See which version you have:
cargo tree -i openssl-src(it also shows which of your dependencies pulls it in). - Update within your version requirement:
cargo update -p openssl-src. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for exampleopenssl-src = "111.15.0") or update the dependency that pulls it in. - Check again with
cargo audit, or paste your Cargo.lock into our Cargo.toml checker.
Details from the advisory
The X509_V_FLAG_X509_STRICT flag enables additional security checks of the certificates present in a certificate chain. It is not set by default.
Starting from OpenSSL version 1.1.1h a check to disallow certificates in the chain that have explicitly encoded elliptic curve parameters was added as an additional strict check.
An error in the implementation of this check meant that the result of a previous check to confirm that certificates in the chain are valid CA certificates was overwritten. This effectively bypasses the check that non-CA certificates must not be able to issue other certificates.
If a "purpose" has been configured then there is a subsequent opportunity for checks that the certificate is a valid CA. All of the named "purpose" values implemented in libcrypto perform this check. Therefore, where a purpose is set the certificate chain will still be rejected even when the strict flag has been used. A purpose is set by default in libssl client and server certificate verification routines, but it can be overridden or removed by an application.
In order to be affected, an application must explicitly set the X509_V_FLAG_X509_STRICT verification flag and either not set a purpose for the certificate verification or, in the case of TLS client or server applications, override the default purpose.
References
- Package: crates.io/crates/openssl-src
- Advisory: rustsec.org/advisories/RUSTSEC-2021-0056.html
- Web: www.openssl.org/news/secadv/20210325.txt
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 openssl-src
- Vulnerability HighRUSTSEC-2020-0015 · 2020-04-25Crash causing Denial of Service attack
- Vulnerability MediumRUSTSEC-2021-0055 · 2021-05-01NULL pointer deref in signature_algorithms processing
- Vulnerability HighRUSTSEC-2021-0057 · 2021-05-01Integer overflow in CipherUpdate
- Vulnerability MediumRUSTSEC-2021-0058 · 2021-05-01Null pointer deref in `X509_issuer_and_serial_hash()`
- Vulnerability CriticalRUSTSEC-2021-0097 · 2021-08-24SM2 Decryption Buffer Overflow
- Vulnerability HighRUSTSEC-2021-0098 · 2021-08-24Read buffer overruns processing ASN.1 strings
- VulnerabilityRUSTSEC-2021-0129 · 2021-12-14Invalid handling of `X509_verify_cert()` internal errors in libssl
- VulnerabilityRUSTSEC-2022-0014 · 2022-03-15Infinite loop in `BN_mod_sqrt()` reachable when parsing certificates
Up next
Same crateopenssl-src: security historyEvery advisory for this crate, and whether it is safe to use today.Read it next →Did this answer your question?