CVE-2021-44758Network attack vector

Server application crash via absent SPNEGO mechanism

Published Dec 26, 2022 · Updated Apr 14, 2025

NULL pointer dereference in Heimdal before 7.7.1 allows remote attackers to crash SPNEGO-enabled server applications with a crafted token. Within lib/gssapi/spnego, acceptor_start passes a nonzero initial_response to send_accept after selecting GSS_C_NO_OID instead of rejecting a token with no acceptable mechanism. Any unauthenticated client able to submit an initial SPNEGO token to a server application using the affected acceptor can interrupt that application by triggering a segmentation fault.

CVSS severity7.5
High
EPSS probability1.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Heimdal before 7.7.1 allows remote attackers to crash SPNEGO-enabled server applications with a crafted token. Within lib/gssapi/spnego, acceptor_start passes a nonzero initial_response to send_accept after selecting GSS_C_NO_OID instead of rejecting a token with no acceptable mechanism. Any unauthenticated client able to submit an initial SPNEGO token to a server application using the affected acceptor can interrupt that application by triggering a segmentation fault.

The record

CVE
CVE-2021-44758
Published
Dec 26, 2022
Updated
Apr 14, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 26, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 14, 2025Record 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

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NVDCVSS: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.

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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 exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Endpoint Denial of Service: Application 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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