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.
CVE-2020-26217
“▲” beside the score: it is higher than NVD's CVSS score.
Score elevated to 9.0 because EPSS predicted 83% probability of exploitation within the next 30 days (99th percentile of EPSS-scored CVEs) when EchelonGraph scored this CVE. NVD baseline CVSS 8.8 retained for reference. Confidence: see factors.
- High exploitation likelihood — EPSS 83%
- Public exploit or proof-of-concept code is available
A fix is available — apply it.
- CVSS v3
- 8.8
- EG Score
- 9.0CRITICALhigh confidence
- EG Risk
- 88EG Risk 88/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity88% × 45%Impact severity (EG Severity): CVSS 8.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation83% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability100% × 15%CISA's SSVC Automatable value: yes (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high. - EPSS PROB
- 83%
- EPSS %ILE
- 99th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (9.0): severity, escalated by confirmed exploitation. This CVE's 9.0 is EPSS's lift toward 9.0 from its impact severity (EG Severity, CVSS 8.8 HIGH): a likelihood of exploitation, not impact.
- EG Severity
- 8.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
- EG Likelihood
- 83% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-22). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)3 days if the affected system is publicly exposed; 60 days if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
November 16, 2020
Last Modified
October 7, 2026
Advisory Details (9)
Auto-updated Sep 20, 2026[SECURITY] [DSA 4811-1] libxstream-java security update
https://www.debian.org/security/2020/dsa-4811[SECURITY] [DLA 2471-1] libxstream-java security update
https://lists.debian.org/debian-lts-announce/2020/12/msg00001.htmlXStream can be used for Remote Code Execution · Advisory · x-stream/xstream · GitHub
https://github.com/x-stream/xstream/security/advisories/GHSA-mw36-7c6c-q4q2commit 0fec095d5341 (x-stream/xstream)
Fix landed in x-stream/xstream commit 0fec095d5341 — awaiting tagged release
https://github.com/x-stream/xstream/commit/0fec095d534126931c99fd38e9c6d41f5c685c1aVendor Advisories for CVE-2020-26217(5)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- RHSA-2021:5134Red Hat Product SecurityCritical
Red Hat Security Advisory: Red Hat Fuse 7.10.0 release and security update
- RHSA-2021:4767Red Hat Product SecurityMedium
Red Hat Security Advisory: Red Hat Integration Camel Extensions for Quarkus GA security update
- RHSA-2021:3205Red Hat Product SecurityMedium
Red Hat Security Advisory: Red Hat Integration Camel-K 1.4 release and security update
- RHSA-2021:0384Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat JBoss Fuse/A-MQ 6.3 R18 security and bug fix update
- RHSA-2021:0105Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Process Automation Manager 7.9.1 security update
Patch Availability(7)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| ubuntu | libxstream-java (1.4.15-1ubuntu0.1) @ hirsute | 2026-10-21 | ubuntu |
| ubuntu | libxstream-java (1.4.11.1-1ubuntu0.1) @ focal | 2026-10-21 | ubuntu |
| ubuntu | libxstream-java (1.4.8-1ubuntu0.1+esm3) @ xenial | 2026-10-21 | ubuntu |
| redhat | xstream | 2021-12-14 | redhat |
| redhat | patch | 2021-11-23 | redhat |
| redhat | patch | 2021-08-18 | redhat |
| redhat | xstream-0:1.3.1-12.el7_9 | 2021-01-18 | redhat |
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
(7 across 7 ecosystems)
Debian:10(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| libxstream-java | 1.4.11.1-1 |
| — |
Debian:11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| libxstream-java | — |
| — |
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| libxstream-java | — |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| libxstream-java | — |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| libxstream-java | — |
| — |
Debian:9(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| libxstream-java | 1.4.9-2 |
| — |
Maven(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| com.thoughtworks.xstream:xstream | 0.1 ... 1.4.9 (37 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Additional Vendor Advisories
(6)
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.
- Red HatRHSA-2021:0106IMPORTANT2020-11-16
RHSA-2021:0106 — Important
- Red HatRHSA-2021:0162IMPORTANT2020-11-16
RHSA-2021:0162 — Important
- Red HatRHSA-2021:0433IMPORTANT2020-11-16
RHSA-2021:0433 — Important
- UbuntuUSN-4714-1MEDIUM
XStream vulnerabilities
- UbuntuUSN-4943-1MEDIUM
XStream vulnerabilities
- UbuntuUSN-6978-1MEDIUM
XStream vulnerabilities
Data Freshness Timeline
(refreshed 18× in last 7d / 40× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
Showing the most recent 89 of 98 refreshes on record for this CVE.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 11 repeat rows among the latest 100 are merged into the row they repeat. The 9 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-10-22 23:16 UTCEG score recompute
- 2026-10-22 23:16 UTCVendor advisory
- 2026-10-22 16:29 UTCEPSS rescoreEPSS 83% · 99th percentile
- 2026-10-22 00:21 UTCEG score recompute
- 2026-10-22 00:21 UTCVendor advisory
- 2026-10-21 16:28 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-10-21 01:24 UTCEG score recompute
- 2026-10-21 01:24 UTCVendor advisory
- 2026-10-20 02:27 UTCEG score recompute
- 2026-10-20 02:27 UTCVendor advisory
- 2026-10-19 16:27 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-10-19 01:51 UTCEG score recompute
- 2026-10-19 01:51 UTCVendor advisory
- 2026-10-18 09:26 UTCEG score recompute
- 2026-10-18 02:53 UTCEG score recompute
- 2026-10-18 02:53 UTCVendor advisory
- 2026-10-17 03:56 UTCEG score recompute
- 2026-10-17 03:56 UTCVendor advisory
- 2026-10-16 16:33 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-10-16 04:57 UTCEG score recompute
- 2026-10-16 04:57 UTCVendor advisory
- 2026-10-15 03:24 UTCEG score recompute
- 2026-10-15 03:24 UTCVendor advisory
- 2026-10-14 16:28 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-10-13 23:36 UTCEG score recompute
Show 64 moreShow fewer
- 2026-10-13 23:36 UTCVendor advisory
- 2026-10-13 16:28 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-10-12 19:40 UTCVendor advisory
- 2026-10-12 19:39 UTCEG score recompute
- 2026-10-12 00:03 UTCEG score recompute
- 2026-10-07 23:44 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-10-07 19:28 UTCEG score recompute
- 2026-10-07 19:28 UTCVendor advisory
- 2026-10-07 19:19 UTCNVD updateCVSS v3 → 8.8
- 2026-10-07 19:03 UTCEG score recompute
- 2026-10-07 19:03 UTCVendor advisory
- 2026-10-03 14:22 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-09-30 20:10 UTCOSV refresh
- 2026-09-30 15:16 UTCEG score recompute
- 2026-09-24 14:00 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-09-22 14:43 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-09-21 20:28 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-09-19 15:37 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-09-18 19:23 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-09-16 14:04 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-09-15 03:06 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-09-12 02:40 UTCOSV refresh
- 2026-09-06 13:44 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-09-05 15:24 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-09-04 13:57 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-09-02 14:08 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-08-30 19:14 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-08-26 14:42 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-08-24 07:58 UTCOSV refresh
- 2026-08-20 22:52 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-08-16 02:11 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-08-13 21:57 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-08-08 16:33 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-08-08 04:49 UTCOSV refresh
- 2026-08-07 16:23 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-07-28 15:33 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-07-26 14:51 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-07-24 14:14 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-07-23 14:15 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-07-23 01:51 UTCEG score recompute
- 2026-07-22 21:28 UTCEG score recompute▲ 1.00
- 2026-07-22 21:28 UTCVendor advisory
- 2026-07-22 14:05 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-07-20 17:04 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-07-16 16:59 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-07-15 16:55 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-07-12 23:07 UTCOSV refresh
- 2026-07-12 05:44 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-07-09 19:07 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-07-07 13:43 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-07-06 16:25 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-07-04 06:29 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-06-27 03:06 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-06-24 14:03 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-06-24 08:50 UTCOSV refresh
- 2026-06-23 21:31 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-06-21 14:54 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-06-16 17:50 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-06-15 17:46 UTCEPSS rescoreEPSS 85% · 99th percentile
- 2026-06-14 23:15 UTCEPSS rescoreEPSS 93% · 99th percentile
- 2026-06-12 23:10 UTCEPSS rescoreEPSS 93% · 99th percentile
- 2026-06-08 14:15 UTCEPSS rescoreEPSS 93% · 99th percentile
- 2026-06-07 15:23 UTCEPSS rescoreEPSS 93% · 99th percentile
- 2026-06-07 12:29 UTCOSV refresh
Publicly available exploits
(4 references)Public exploit code is referenced for this CVE (3 GitHub PoCs), as is 1 Nuclei detection template. A detection template checks whether a system is affected; it is not necessarily exploit code. Defenders should treat patch urgency accordingly.
- GitHub PoCKairo-one/CVE-2020-26217-XStreamPublished Dec 1, 2025
CVE-2020-26217 XStream反序列化的poc
Open source ↗ - Nucleihttp/cves/2020/CVE-2020-26217.yamlPublished Mar 29, 2023
XStream <1.4.14 - Remote Code Execution
Open source ↗ - GitHub PoCAl1ex/CVE-2020-26217Published Jan 22, 2021
CVE-2020-26217 && XStream RCE
Open source ↗ - GitHub PoCnovysodope/CVE-2020-26217-XStream-RCE-POCPublished Dec 8, 2020
CVE-2020-26217 XStream RCE POC
Open source ↗
Related CVEs(same product + same vendor + same CWE)
Same product
10 shownDebian:10:libxstream-java
- CVE-2021-39144NVD 8.5EG 9.0 KEVEPSS p100CRITICAL
- CVE-2020-26259NVD 6.8EG 8.9EPSS p100HIGH
- CVE-2020-26258NVD 7.7EG 8.9EPSS p100HIGH
- CVE-2021-39139EG 8.8EPSS p92HIGH
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- CVE-2021-39150EG 8.5HIGH
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- CVE-2021-39153EG 8.5EPSS p91HIGH
- CVE-2021-39151EG 8.5EPSS p92HIGH
- CVE-2021-39149EG 8.5EPSS p92HIGH
Same vendor
10 shownredhat:RHSA-2021:3205 · redhat:RHSA-2021:4767
- CVE-2020-26259NVD 6.8EG 8.9EPSS p100HIGH
- CVE-2020-26258NVD 7.7EG 8.9EPSS p100HIGH
- CVE-2021-21345EG 9.9EPSS p99CRITICAL
- CVE-2021-21350EG 9.8EPSS p97CRITICAL
- CVE-2021-21347EG 9.8EPSS p97CRITICAL
- CVE-2021-21346EG 9.8EPSS p100CRITICAL
- CVE-2021-21344EG 9.8EPSS p100CRITICAL
- CVE-2021-21351EG 9.1EPSS p100CRITICAL
- CVE-2021-21342EG 9.1EPSS p99CRITICAL
- CVE-2021-21341NVD 7.5EG 8.8EPSS p100HIGH
Same CWE
10 shownCWE-78
Frequently asked(5)
What is CVE-2020-26217?
When was the CVE record for CVE-2020-26217 published?
Is CVE-2020-26217 actively exploited?
What is the CVSS score of CVE-2020-26217?
How do I remediate CVE-2020-26217?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2020-26217
Is Your Infrastructure Affected by CVE-2020-26217?
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