CVE-2021-31663Public exploitNetwork attack vector

Information disclosure via URI parser out-of-bounds read

Published Jun 18, 2021 · Updated Aug 3, 2024

Out-of-bounds read in the URI parser in RIOT-OS 2021.01 allows remote attackers to read sensitive memory via a crafted absolute URI. The _consume_userinfo function advances result->host by the userinfo length plus one without checking authority_end, so A://@ moves the host pointer beyond its five-byte buffer. No authentication or user interaction is required, and the demonstrated consequence is a one-byte read of adjacent memory.

CVSS severity7.5
High
EPSS probability1.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in the URI parser in RIOT-OS 2021.01 allows remote attackers to read sensitive memory via a crafted absolute URI. The _consume_userinfo function advances result->host by the userinfo length plus one without checking authority_end, so A://@ moves the host pointer beyond its five-byte buffer. No authentication or user interaction is required, and the demonstrated consequence is a one-byte read of adjacent memory.

The record

CVE
CVE-2021-31663
Published
Jun 18, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-120
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 18, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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:P/I:N/A:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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.

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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 exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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