CVE-2020-26217

HIGHNVD 8.08.0
EchelonGraph scoreLOW confidence

This high-severity CVE scores 8.0 under NVD CVSS v3. EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: nvd
Elevated
8.0
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 85%
CISA-KEV: Not listedEPSS: 85%CVSS: 8.0Exploit: NoneExposed: 0

A fix is available — apply it.

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.

CVSS v3
8.0
EG Score
8.0(low)
EPSS
99.7%
KEV
Not listed

Published

November 16, 2020

Last Modified

May 23, 2025

References (30)

Vendor Advisories for CVE-2020-26217(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(7)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibxstream-java (1.4.11.1-1~18.04.1) @ bionic2026-05-23ubuntu
ubuntulibxstream-java (1.4.15-1ubuntu0.1) @ hirsute2026-05-23ubuntu
ubuntulibxstream-java (1.4.8-1ubuntu0.1+esm3) @ xenial2026-05-23ubuntu
redhatxstream2021-12-14redhat
redhatpatch2021-11-23redhat
redhatpatch2021-08-18redhat
redhatxstream-0:1.3.1-12.el7_92021-01-18redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
Maven(1)
PackageVulnerable rangeFixed inDependents
com.thoughtworks.xstream:xstream0.1 ... 1.4.9 (37 versions)1.4.14-java7—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(9)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 4× in last 7d / 19× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-09 19:07 UTCEPSS rescore
  2. 2026-07-07 13:43 UTCEPSS rescore
  3. 2026-07-06 16:25 UTCEPSS rescore
  4. 2026-07-06 16:25 UTCEPSS rescore
  5. 2026-07-04 06:29 UTCEPSS rescore
  6. 2026-07-04 06:29 UTCEPSS rescore
  7. 2026-06-27 03:06 UTCEPSS rescore
  8. 2026-06-27 03:06 UTCEPSS rescore
  9. 2026-06-24 14:03 UTCEPSS rescore
  10. 2026-06-24 14:03 UTCEPSS rescore
  11. 2026-06-24 08:50 UTCOSV refresh
  12. 2026-06-23 21:31 UTCEPSS rescore
  13. 2026-06-23 21:31 UTCEPSS rescore
  14. 2026-06-21 14:54 UTCEPSS rescore
  15. 2026-06-21 14:54 UTCEPSS rescore
  16. 2026-06-16 17:50 UTCEPSS rescore
  17. 2026-06-15 17:46 UTCEPSS rescore
  18. 2026-06-14 23:15 UTCEPSS rescore
  19. 2026-06-12 23:10 UTCEPSS rescore
  20. 2026-06-08 14:15 UTCEPSS rescore
  21. 2026-06-08 14:15 UTCEPSS rescore
  22. 2026-06-07 15:23 UTCEPSS rescore
  23. 2026-06-07 15:23 UTCEPSS rescore
  24. 2026-06-07 12:29 UTCOSV refresh
  25. 2026-06-06 13:45 UTCEPSS rescore
Show 8 more
  1. 2026-06-06 13:45 UTCEPSS rescore
  2. 2026-06-02 20:11 UTCEPSS rescore
  3. 2026-06-02 20:11 UTCEPSS rescore
  4. 2026-05-27 13:39 UTCEPSS rescore
  5. 2026-05-26 07:17 UTCEPSS rescore
  6. 2026-05-26 07:17 UTCEPSS rescore
  7. 2026-05-23 05:09 UTCEG score recompute
  8. 2026-05-23 05:09 UTCVendor advisory

Publicly available exploits

(4 references)

Working exploit code is in the public domain (3 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCKairo-one/CVE-2020-26217-XStream
    First seen Dec 1, 2025

    CVE-2020-26217 XStream反序列化的poc

    Open source ↗
  • GitHub PoCAl1ex/CVE-2020-26217
    First seen Jan 22, 2021

    CVE-2020-26217 && XStream RCE

    Open source ↗
  • GitHub PoCnovysodope/CVE-2020-26217-XStream-RCE-POC
    First seen Dec 8, 2020

    CVE-2020-26217 XStream RCE POC

    Open source ↗
  • Nucleihttp/cves/2020/CVE-2020-26217.yaml
    First seen Jan 1, 2020

    XStream <1.4.14 - Remote Code Execution

    Open source ↗

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2020-26217?
CVE-2020-26217 is a high vulnerability published on November 16, 2020. 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…
When was CVE-2020-26217 disclosed?
CVE-2020-26217 was first published in the National Vulnerability Database on November 16, 2020, with the most recent update on May 23, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2020-26217 actively exploited?
CVE-2020-26217 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 99.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2020-26217?
CVE-2020-26217 has a CVSS v3 base score of 8.0 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2020-26217?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-26217, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2020-26217

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