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CVE Record

CVE-2021-36770: Encode.pm, as distributed in Perl through 5.34.0, allows local users to gain privileges via a Trojan horse...

Encode.pm, as distributed in Perl through 5.34.0, allows local users to gain privileges via a Trojan horse Encode::ConfigLocal library (in the current working directory) that preempts dynamic module loading. Exploitation requires an unusual configuration, and certain 2021 versions of Encode.pm (3.05 through 3.11). This issue occurs because the || operator evaluates @INC in a scalar context, and thus @INC has only an integer value.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-36770 is a constrained local privilege-escalation issue in Perl's Encode.pm. A local user may gain privileges if an affected Encode.pm version loads a malicious local configuration library from the current directory. The sources stress unusual configuration requirements, so urgency depends on whether affected Perl or Encode versions exist in privileged workflows.

Executive priority

Treat as a targeted local privilege-escalation risk, not a broad remote emergency. Prioritize managed servers, hosting platforms, and appliances where Perl runs with elevated privileges, then close with vendor-supported updates.

Technical view

Encode.pm versions 3.05 through 3.11, distributed with Perl through 5.34.0, mishandle @INC because || evaluates it in scalar context. That can let Encode::ConfigLocal in the current working directory preempt intended dynamic module loading. Vendor commits and advisories indicate updates were issued, but the bundle provides no CVSS vector.

Likely exposure

Exposure is most likely on systems with Perl through 5.34.0 or Encode.pm 3.05-3.11, especially where privileged Perl processes run from writable or user-controlled directories. General internet-facing exposure is not indicated by the source bundle.

Exploitation context

The bundle does not show CISA KEV listing or active exploitation evidence. Exploitation is local and requires unusual configuration plus a Trojan horse Encode::ConfigLocal library positioned where dynamic loading will prefer it.

Researcher notes

Evidence is strongest for the root cause, affected Encode.pm range, and upstream fixes. Product impact outside Perl, distro packages, cPanel, Fedora, Debian, and NetApp should not be inferred without vendor confirmation.

Mitigation direction

  • Inventory Perl and Encode.pm versions across servers and appliances.
  • Prioritize updates for Encode.pm 3.05 through 3.11.
  • Apply relevant OS, Perl, cPanel, Fedora, Debian, or NetApp vendor guidance.
  • Review privileged Perl workflows that run from writable directories.
  • Check vendor advisories before assuming a complete fix path.

Validation and detection

  • Confirm installed Perl and Encode.pm versions on managed hosts.
  • Verify vendor package updates include the referenced Encode or perl5 fixes.
  • Identify privileged jobs or scripts that invoke Perl from writable paths.
  • Check relevant working directories for unexpected Encode::ConfigLocal files.
  • Record exceptions where vendor status is unavailable or unclear.
Prepared
Confidence
medium
Sources
11

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2021-36770 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
10Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

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