How severe is CVE-2021-45711?

No CVSS score has been assigned to CVE-2021-45711 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2021-45711?

CVE-2021-45711 affects the following packages: simple_asn1 (crates.io). Ecosystems affected: crates.io.

How do I fix CVE-2021-45711?

Update simple_asn1 to 0.6.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-45711 is resolved across your whole dependency graph.

How do I detect CVE-2021-45711 in my crates.io dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for simple_asn1, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-45711 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2021-45711?

O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2021-45711 can be triaged on real exposure rather than presence alone.

Is CVE-2021-45711 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-45711 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-45711?

CVE-2021-45711 has an EPSS (Exploit Prediction Scoring System) score of 1.3%, placing it in the 70th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-45711?

CVE-2021-45711 is classified as Improper Input Validation (CWE-20). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-45711 published, and has it been updated?

CVE-2021-45711 was published on June 17, 2022 and was last updated on November 8, 2023. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🦀 crates.io

Not in CISA KEV

CVE-2021-45711 — simple_asn1

Fix: acw/simple_asn1@d7d39d7

CVE-2021-45711 is a Improper Input Validation vulnerability in simple_asn1. A fix is available for simple_asn1 — see the affected versions and patch details below.

Panic on incorrect date input to `simple_asn1`

Also known asGHSA-g4h2-4wvh-grc5RUSTSEC-2021-0125

Published

Jun 17, 2022

Updated

Nov 8, 2023

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Sep 21, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs70th percentile — riskier than 70% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

1 pkg affected

🦀simple_asn1

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.

Description

Version 0.6.0 of the simple_asn1 crate panics on certain malformed inputs to its parsing functions, including from_der and der_decode. Because this crate is frequently used with inputs from the network, this should be considered a security vulnerability.

The issue occurs when parsing the old ASN.1 "UTCTime" time format. If an attacker provides a UTCTime where the first character is ASCII but the second character is above 0x7f, a string slice operation in the from_der_ function will try to slice into the middle of a UTF-8 character, and cause a panic.

This error was introduced in commit d7d39d709577710e9dc8, which updated simple_asn1 to use time instead of chrono because of RUSTSEC-2020-159. Versions of simple_asn1 before 0.6.0 are not affected by this issue.

The patch was applied in simple_asn1 version 0.6.1.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`simple_asn1`	≥ 0.6.0&&< 0.6.1	0.6.1`cargo update -p simple_asn1 --precise 0.6.1`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for simple_asn1, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update simple_asn1 to 0.6.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-45711 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2021-45711 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2021-45711. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Version 0.6.0 of the `simple_asn1` crate panics on certain malformed inputs to its parsing functions, including `from_der` and `der_decode`. Because this crate is frequently used with inputs from the network, this should be considered a security vulnerability. The issue occurs when parsing the old ASN.1 "UTCTime" time format. If an attacker provides a UTCTime where the first character is ASCII but the second character is above 0x7f, a string slice operation in the `from_der_` function will try to slice into the middle of a UTF-8 character, and cause a panic. This error was introduced in com

O3 Security · Impact-Aware SCA

Is CVE-2021-45711 in your dependencies?

O3 Security finds CVE-2021-45711 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

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