CVE-2021-3826Public exploitNetwork attack vector

Demangler crash via unchecked null parse result

Published Sep 1, 2022 · Updated Aug 3, 2024

Null-pointer dereference in GNU Compiler Collection 11.2.0 allows remote attackers to crash a demangler via a crafted D symbol. In libiberty/d-demangle.c, dlang_type dereferences a null mangled pointer returned while parsing malformed input before testing for a D type back-reference. Triggering the crash requires a person or downstream tool to pass an attacker-controlled mangled D symbol to the affected demangler; the reported consequence is process termination.

CVSS severity6.5
Medium
EPSS probability1.37%
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 GNU Compiler Collection 11.2.0 allows remote attackers to crash a demangler via a crafted D symbol. In libiberty/d-demangle.c, dlang_type dereferences a null mangled pointer returned while parsing malformed input before testing for a D type back-reference. Triggering the crash requires a person or downstream tool to pass an attacker-controlled mangled D symbol to the affected demangler; the reported consequence is process termination.

The record

CVE
CVE-2021-3826
Published
Sep 1, 2022
Updated
Aug 3, 2024
Vendor
GNU Project
Product
GNU Compiler Collection
Classifications
CWE-787, CWE-119, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 1, 2022CVE 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=gcc 11.2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

GNU Project · GNU Compiler Collectionversion=gcc 11.2.0

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/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-787Out-of-bounds Write
CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
T1499.004Application 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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