CVE-2021-45711Network attack vector

Service interruption via malformed UTCTime slicing

Published Dec 26, 2021 · Updated Aug 4, 2024

Denial of service in simple_asn1 0.6.0 allows remote attackers to trigger a panic by supplying malformed ASN.1 UTCTime data. The from_der_ parser slices the UTCTime string at a byte boundary after only the first character is confirmed as ASCII, so a non-ASCII second character splits a UTF-8 sequence and panics. Exploitation requires a consuming application to pass attacker-controlled DER to from_der or der_decode, and the panic interrupts availability according to that application's panic handling.

CVSS severity7.5
High
EPSS probability1.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in simple_asn1 0.6.0 allows remote attackers to trigger a panic by supplying malformed ASN.1 UTCTime data. The from_der_ parser slices the UTCTime string at a byte boundary after only the first character is confirmed as ASCII, so a non-ASCII second character splits a UTF-8 sequence and panics. Exploitation requires a consuming application to pass attacker-controlled DER to from_der or der_decode, and the panic interrupts availability according to that application's panic handling.

The record

CVE
CVE-2021-45711
Published
Dec 26, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-20, CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 26, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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