CVE-2021-26958Network attack vector

Memory corruption via unconstrained event transmutation

Published Feb 9, 2021 · Updated Aug 3, 2024

Memory corruption in the Rust xcb crate before 1.0.0 allows attackers to corrupt or expose memory through an invalid event cast. xcb::base::cast_event directly transmutes a GenericEvent reference to an unconstrained caller-selected type, including types larger than the 32-byte event. Exploitation requires a consuming program to call the safe API with an incorrect inferred or requested type; resulting behavior is application-dependent.

CVSS severity8.8
High
EPSS probability1.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory corruption in the Rust xcb crate before 1.0.0 allows attackers to corrupt or expose memory through an invalid event cast. xcb::base::cast_event directly transmutes a GenericEvent reference to an unconstrained caller-selected type, including types larger than the 32-byte event. Exploitation requires a consuming program to call the safe API with an incorrect inferred or requested type; resulting behavior is application-dependent.

The record

CVE
CVE-2021-26958
Published
Feb 9, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-252
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 9, 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 privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.5NIST NVDAV:N/AC:L/Au:S/C:P/I:P/A:P

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-252Unchecked Return Value

Public exploit references

No public exploit references are available in this record.

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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