CVE-2021-3326Public exploitNetwork attack vector

Application crash via premature full-output return

Published Jan 27, 2021 · Updated Jun 9, 2025

Reachable assertion in GNU C Library 2.32 and earlier allows remote attackers to crash applications via crafted ISO-2022-JP-3 input. The conversion loop returns __GCONV_FULL_OUTPUT before filling the internal wide-character buffer when a two-character combined sequence crosses a buffer boundary, violating the iconv contract and tripping an assertion. Exploitation requires an application to pass attacker-controlled ISO-2022-JP-3 data to iconv; the resulting abort halts that process without reported data exposure or modification.

CVSS severity7.5
High
EPSS probability3.09%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reachable assertion in GNU C Library 2.32 and earlier allows remote attackers to crash applications via crafted ISO-2022-JP-3 input. The conversion loop returns __GCONV_FULL_OUTPUT before filling the internal wide-character buffer when a two-character combined sequence crosses a buffer boundary, violating the iconv contract and tripping an assertion. Exploitation requires an application to pass attacker-controlled ISO-2022-JP-3 data to iconv; the resulting abort halts that process without reported data exposure or modification.

The record

CVE
CVE-2021-3326
Published
Jan 27, 2021
Updated
Jun 9, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-617, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 27, 2021CVE publishedPublication date reported by the CVE source.
  2. Jun 9, 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

7.5CanonicalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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

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-617Reachable Assertion
T1499.004Endpoint Denial of Service: Application or System Exploitation

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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