CVE-2021-27919Public exploit

Application crash via incorrect traversal-prefix loop

Published Mar 11, 2021 · Updated Aug 3, 2024

A denial of service in Go 1.16.0 archive/zip allows attackers to crash applications that call Reader.Open on a crafted ZIP archive. The toValidName function tests the unchanged original filename while repeatedly shortening its cleaned path, so a leading ../ prefix eventually triggers a panic. An application must parse an attacker-supplied archive through Reader.Open; an unrecovered panic terminates the affected process.

CVSS severity5.5
Medium
EPSS probability1.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A denial of service in Go 1.16.0 archive/zip allows attackers to crash applications that call Reader.Open on a crafted ZIP archive. The toValidName function tests the unchanged original filename while repeatedly shortening its cleaned path, so a leading ../ prefix eventually triggers a panic. An application must parse an attacker-supplied archive through Reader.Open; an unrecovered panic terminates the affected process.

The record

CVE
CVE-2021-27919
Published
Mar 11, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1499.004
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 11, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

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.

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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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

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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