CVE-2021-20284

Process crash via incorrect dynamic symbol count

Published Mar 26, 2021 · Updated Aug 3, 2024

Heap-based buffer overflow in The GnuPG Project GNU Binutils 2.35.1 allows remote attackers to crash a Binutils process via a crafted ELF file. The _bfd_elf_slurp_secondary_reloc_section function uses the regular symbol count while processing dynamic relocations, so indexed writes can exceed the allocated symbol-backed buffer. Exploitation requires a victim or local toolchain workflow to process the crafted file; the documented consequence is an availability-only process crash.

CVSS severity5.5
Medium
EPSS probability1.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in The GnuPG Project GNU Binutils 2.35.1 allows remote attackers to crash a Binutils process via a crafted ELF file. The _bfd_elf_slurp_secondary_reloc_section function uses the regular symbol count while processing dynamic relocations, so indexed writes can exceed the allocated symbol-backed buffer. Exploitation requires a victim or local toolchain workflow to process the crafted file; the documented consequence is an availability-only process crash.

The record

CVE
CVE-2021-20284
Published
Mar 26, 2021
Updated
Aug 3, 2024
Vendor
The GnuPG Project
Product
GNU Binutils
Classifications
CWE-119, CWE-787, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 26, 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?

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

  1. Affected versionversion=Binutils 2.35.1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

The GnuPG Project · GNU Binutilsversion=Binutils 2.35.1

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P
5.5NIST NVDCVSS:3.1/AV:L/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-787Out-of-bounds Write
T1204.002User Execution: Malicious File

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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