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CVE Record

CVE-2020-26217: Remote Code Execution in XStream

XStream before version 1.4.14 is vulnerable to Remote Code Execution.The vulnerability may allow a remote attacker to run arbitrary shell commands only by manipulating the processed input stream. Only users who rely on blocklists are affected. Anyone using XStream's Security Framework allowlist is not affected. The linked advisory provides code workarounds for users who cannot upgrade. The issue is fixed in version 1.4.14.

HighCVSS 8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

XStream versions before 1.4.14 can let an attacker execute shell commands if vulnerable applications process manipulated input streams. The highest risk is where XStream handles attacker-influenced data and uses blocklist-based security. Applications using XStream's allowlist Security Framework are stated as not affected.

Executive priority

Prioritize remediation for internet-facing, integration-facing, or workflow-critical Java systems that deserialize input with XStream. Treat as high severity because successful exploitation could execute commands, but scope remediation by configuration and reachability because allowlist users are stated as not affected.

Technical view

CVE-2020-26217 is CWE-78 command injection in x-stream:xstream before 1.4.14. The advisory says attackers may run arbitrary shell commands by manipulating processed input. The CVSS 3.1 score is 8.0 with high impact but higher exploitation conditions: PR:L, UI:R, AC:H, and changed scope.

Likely exposure

Exposure is most likely in Java applications or products bundling XStream below 1.4.14, especially where serialized input can be influenced by users or integrations. Blocklist-based configurations are the stated affected case; allowlist Security Framework configurations are stated as not affected.

Exploitation context

The source bundle does not show KEV listing or confirmed active exploitation. The advisory describes remote code execution potential, but the CVSS vector indicates exploitation is not trivial and requires privileges, user interaction, and high attack complexity.

Researcher notes

Focus analysis on XStream call sites, dependency trees, shaded jars, and product-bundled copies. Do not assume all XStream usage is exploitable; the decisive factors are version, Security Framework allowlist use, and whether attacker-influenced streams reach XStream processing.

Mitigation direction

  • Upgrade XStream to version 1.4.14 or later.
  • Prefer XStream Security Framework allowlists over blocklist-only controls.
  • Apply vendor package updates for bundled or distribution-managed XStream.
  • If upgrade is blocked, review the XStream advisory workarounds.
  • Check downstream vendor advisories for affected products before manual library replacement.

Validation and detection

  • Inventory applications and products containing XStream or libxstream-java.
  • Confirm any XStream version is 1.4.14 or newer.
  • Review XStream configuration for allowlist-based Security Framework use.
  • Identify whether XStream processes untrusted or integration-supplied input streams.
  • Verify vendor-applied updates for Debian, Oracle, NetApp, or packaged dependencies.
Prepared
Confidence
high
Sources
8

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

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · medium confidence lookup

CWE-78: Command execution behavior lookup

Command injection weaknesses can lead defenders to review execution techniques and command interpreter telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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description · low confidence lookup

Execution behavior lookup

The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2020-26217 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H

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.

1CVSS vectors
0Timeline events
0ADP providers
16Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
8CVSS 3.1HighCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H1.36Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

8High
CVSS 3.1 vector shape for CVE-2020-26217Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
x-streamxstream< 1.4.14Listed
Weakness

CWE details

CWE-78

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-78 · source CWE mapping

Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs