CVE-2020-27618Public exploit

Process hang via unconsumed redundant shift sequence

Published Feb 26, 2021 · Updated Jun 9, 2025

Infinite loop in GNU C Library iconv 2.32 and earlier allows local users to hang applications via crafted IBM multibyte input. The shared iconvdata/ibm1364.c converter rejects redundant shift-in or shift-out sequences without consuming them, so processing repeats indefinitely. The application must invoke iconv on attacker-controlled data using IBM1364, IBM1371, IBM1388, IBM1390, or IBM1399, and the impact is limited to a process hang.

CVSS severity5.5
Medium
EPSS probability0.89%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Infinite loop in GNU C Library iconv 2.32 and earlier allows local users to hang applications via crafted IBM multibyte input. The shared iconvdata/ibm1364.c converter rejects redundant shift-in or shift-out sequences without consuming them, so processing repeats indefinitely. The application must invoke iconv on attacker-controlled data using IBM1364, IBM1371, IBM1388, IBM1390, or IBM1399, and the impact is limited to a process hang.

The record

CVE
CVE-2020-27618
Published
Feb 26, 2021
Updated
Jun 9, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-835, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 26, 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 vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

2.1NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:P
5.5CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499.004Application or System Exploitation

Public exploit references

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Technologies

Your stack

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Your stack

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