CVE-2021-32557Public exploit

Administrator file overwrite via symbolic-link following

Published Jun 12, 2021 · Updated Sep 16, 2024

Improper link handling in Canonical Apport allows local users to overwrite arbitrary files as an administrator via crafted symlinks. The process_report() function in data/whoopsie-upload-all writes report data through attacker-controlled symbolic-link paths instead of rejecting links before file access. Low-privileged local access is required; successful exploitation modifies administrator-owned files and can interrupt dependent services.

CVSS severity7.1
High
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper link handling in Canonical Apport allows local users to overwrite arbitrary files as an administrator via crafted symlinks. The process_report() function in data/whoopsie-upload-all writes report data through attacker-controlled symbolic-link paths instead of rejecting links before file access. Low-privileged local access is required; successful exploitation modifies administrator-owned files and can interrupt dependent services.

The record

CVE
CVE-2021-32557
Published
Jun 12, 2021
Updated
Sep 16, 2024
Vendor
Canonical
Product
Apport
Classifications
CWE-59, CWE-61, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 12, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=2.14.1-0ubuntu3 <2.14.1-0ubuntu3.29+esm7
  2. Affected versionversion=2.20.11-0ubuntu27 <2.20.11-0ubuntu27.18
  3. Affected versionversion=2.20.11-0ubuntu50 <2.20.11-0ubuntu50.7
  4. Affected versionversion=2.20.11-0ubuntu65 <2.20.11-0ubuntu65.1
  5. Affected versionversion=2.20.1 <2.20.1-0ubuntu2.30+esm1
  6. Affected versionversion=2.20.9 <2.20.9-0ubuntu7.24

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Canonical · Apportversion=2.14.1-0ubuntu3 <2.14.1-0ubuntu3.29+esm7; version=2.20.11-0ubuntu27 <2.20.11-0ubuntu27.18; version=2.20.11-0ubuntu50 <2.20.11-0ubuntu50.7; version=2.20.11-0ubuntu65 <2.20.11-0ubuntu65.1; version=2.20.1 <2.20.1-0ubuntu2.30+esm1; version=2.20.9 <2.20.9-0ubuntu7.24

Published CVSS scores

5.2Canonical Ltd.CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:L
3.6NIST NVDAV:L/AC:L/Au:N/C:N/I:P/A:P
7.1NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-59Improper Link Resolution Before File Access ('Link Following')
CWE-61UNIX Symbolic Link (Symlink) Following
T1068Exploitation for Privilege Escalation

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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