XStream is a Java library to serialize objects to XML and back again. In XStream before version 1.4.15, a Server-Side Forgery Request vulnerability can be activated when unmarshalling. The vulnerability may allow a remote attacker to request data from internal resources that are not publicly available only by manipulating the processed input stream. If you rely on XStream's default blacklist of the Security Framework, you will have to use at least version 1.4.15. The reported vulnerability does not exist if running Java 15 or higher. No user is affected who followed the recommendation to setup XStream's Security Framework with a whitelist! Anyone relying on XStream's default blacklist can immediately switch to a whilelist for the allowed types to avoid the vulnerability. Users of XStream 1.4.14 or below who still want to use XStream default blacklist can use a workaround described in more detailed in the referenced advisories.
CVE-2020-26258
“▲” beside the score: it is higher than NVD's CVSS score.
Score elevated to 8.9 because EPSS predicted 82% probability of exploitation within the next 30 days (99th percentile of EPSS-scored CVEs) when EchelonGraph scored this CVE. NVD baseline CVSS 7.7 retained for reference. Confidence: see factors.
Also known asEUVD-2020-1481 (ENISA EUVD) · GHSA-4cch-wxpw-8p28 (GitHub Security Advisories)Source: ENISA EUVD
- High exploitation likelihood — EPSS 82%
A fix is available — apply it.
- CVSS v3
- 7.7
- EG Score
- 8.9HIGHhigh confidence
- EG Risk
- 82EG Risk 82/100
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)Severity77% × 45%Impact severity (EG Severity): CVSS 7.7 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation82% × 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 partial (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
- 82%
- 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 (8.9): severity, escalated by confirmed exploitation. This CVE's 8.9 is EPSS's lift toward 9.0 from its impact severity (EG Severity, CVSS 7.7 HIGH): a likelihood of exploitation, not impact.
- EG Severity
- 7.7 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
- 82% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). 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: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: 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 partial (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)14 days if the affected system is publicly exposed; 60 days if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (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
December 16, 2020
Last Modified
October 7, 2026
Advisory Details (9)
Auto-updated Oct 7, 2026[SECURITY] [DSA 4828-1] libxstream-java security update
https://www.debian.org/security/2021/dsa-4828[SECURITY] Fedora 34 Update: xstream-1.4.18-2.fc34 - package-announce - Fedora mailing-lists
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QGXIU3YDPG6OGTDHMBLAFN7BPBERXREB[SECURITY] Fedora 35 Update: xstream-1.4.18-2.fc35 - package-announce - Fedora mailing-lists
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PVPHZA7VW2RRSDCOIPP2W6O5ND254TU7[SECURITY] Fedora 33 Update: xstream-1.4.18-2.fc33 - package-announce - Fedora mailing-lists
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/22KVR6B5IZP3BGQ3HPWIO2FWWCKT3DHP[SECURITY] [DLA 2507-1] libxstream-java security update
https://lists.debian.org/debian-lts-announce/2020/12/msg00042.htmlPony Mail
https://lists.apache.org/thread.html/r97993e3d78e1f5389b7b172ba9f308440830ce5f051ee62714a0aa34@%3Ccommits.struts.apache.org%3EA Server-Side Forgery Request can be activated unmarshalling with XStream · Advisory · x-stream/xstream · GitHub
https://github.com/x-stream/xstream/security/advisories/GHSA-4cch-wxpw-8p28Vendor Advisories for CVE-2020-26258(5)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- 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-2021:3140Red Hat Product SecurityMedium
Red Hat Security Advisory: Red Hat Fuse 7.9.0 release and security update
- RHSA-2021:2476Red Hat Product SecurityMedium
Red Hat Security Advisory: Red Hat Decision Manager 7.11.0 security update
- RHSA-2021:2475Red Hat Product SecurityMedium
Red Hat Security Advisory: Red Hat Process Automation Manager 7.11.0 security update
Patch Availability(7)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| ubuntu | libxstream-java (1.4.11.1-2ubuntu0.1) @ groovy | 2026-10-28 | ubuntu |
| ubuntu | libxstream-java (1.4.11.1-1ubuntu0.1) @ focal | 2026-10-28 | ubuntu |
| ubuntu | libxstream-java (1.4.8-1ubuntu0.1+esm3) @ xenial | 2026-10-28 | ubuntu |
| redhat | patch | 2021-11-23 | redhat |
| redhat | patch | 2021-08-18 | redhat |
| redhat | xstream | 2021-08-11 | redhat |
| maven | com.thoughtworks.xstream:xstream @ 1.4.15 (fixes < 1.4.15) | — | ghsa |
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, 1.4.11.1-1+deb10u1 |
| — |
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 | 1.4.10-1, 1.4.11-1, 1.4.11.1-1, 1.4.9-2, 1.4.9-2+deb9u1 |
| — |
Maven(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| com.thoughtworks.xstream:xstream | 0.1 ... 1.4.9 (39 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Additional Vendor Advisories
(4)
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 7× in last 7d / 30× 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 90 of 94 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. 10 repeat rows among the latest 100 are merged into the row they repeat. The 4 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-01 08:36 UTCGHSA enrichmentGHSA-4cch-wxpw-8p28 · GitHub severity MODERATE · GitHub CVSS 6.3
- 2026-11-01 08:36 UTCEG score recompute
- 2026-10-30 16:29 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-10-28 22:54 UTCEG score recompute
- 2026-10-28 22:54 UTCVendor advisory
- 2026-10-28 16:28 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-10-27 16:28 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-10-25 18:46 UTCEG score recompute
- 2026-10-25 16:28 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-10-21 16:28 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-10-21 12:20 UTCEG score recompute
- 2026-10-21 12:20 UTCVendor advisory
- 2026-10-19 16:27 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-10-18 16:28 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-10-18 09:26 UTCEG score recompute
- 2026-10-17 16:28 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-10-16 16:33 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-10-14 16:28 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-10-13 16:28 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-10-12 19:39 UTCEG score recompute
- 2026-10-12 16:29 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-10-12 00:02 UTCEG score recompute
- 2026-10-11 13:43 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-10-07 23:44 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-10-07 19:28 UTCEG score recompute▲ 0.10
Show 65 moreShow fewer
- 2026-10-07 19:28 UTCVendor advisory
- 2026-10-07 19:19 UTCNVD updateCVSS v3 → 7.7 · severity → HIGH
- 2026-10-07 18:47 UTCEG score recompute
- 2026-10-07 18:47 UTCVendor advisory
- 2026-10-06 15:13 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-09-30 15:16 UTCEG score recompute
- 2026-09-30 14:59 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-09-29 15:14 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-09-24 14:00 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-09-22 14:43 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-09-21 20:28 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-09-19 18:33 UTCOSV refresh
- 2026-09-18 19:23 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-09-17 19:22 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-09-16 14:04 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-09-12 14:57 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-09-08 21:56 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-09-07 15:57 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-09-06 13:44 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-09-05 15:24 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-09-04 05:03 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-09-01 03:32 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-08-31 22:04 UTCOSV refresh
- 2026-08-30 19:14 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-08-27 14:21 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-08-26 14:42 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-08-21 23:45 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-08-19 17:00 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-08-18 13:44 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-08-16 02:11 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-08-15 01:26 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-08-14 23:54 UTCOSV refresh
- 2026-08-12 13:47 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-08-02 02:23 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-08-01 04:12 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-07-30 12:14 UTCOSV refresh
- 2026-07-26 14:51 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-07-24 14:14 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-07-23 01:51 UTCEG score recompute▲ 2.50
- 2026-07-22 22:37 UTCEG score recompute
- 2026-07-22 14:05 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-07-20 17:04 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-07-15 16:55 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-07-15 01:57 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-07-12 21:37 UTCOSV refresh
- 2026-07-12 05:44 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-07-09 19:07 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-07-06 02:21 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-07-04 06:29 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-06-28 04:54 UTCEPSS rescoreEPSS 82% · 99th percentile
- 2026-06-25 13:48 UTCEPSS rescoreEPSS 81% · 99th percentile
- 2026-06-24 07:20 UTCOSV refresh
- 2026-06-23 21:31 UTCEPSS rescoreEPSS 81% · 99th percentile
- 2026-06-21 14:54 UTCEPSS rescoreEPSS 81% · 99th percentile
- 2026-06-21 01:57 UTCEPSS rescoreEPSS 81% · 99th percentile
- 2026-06-17 17:50 UTCEPSS rescoreEPSS 81% · 99th percentile
- 2026-06-15 17:46 UTCEPSS rescoreEPSS 81% · 99th percentile
- 2026-06-13 22:58 UTCEPSS rescoreEPSS 94% · 99th percentile
- 2026-06-10 22:16 UTCEPSS rescoreEPSS 94% · 99th percentile
- 2026-06-08 14:15 UTCEPSS rescoreEPSS 94% · 99th percentile
- 2026-06-07 10:59 UTCOSV refresh
- 2026-06-04 13:10 UTCEPSS rescoreEPSS 94% · 99th percentile
- 2026-05-28 13:43 UTCEPSS rescoreEPSS 94% · 99th percentile
- 2026-05-27 13:39 UTCEPSS rescoreEPSS 94% · 99th percentile
- 2026-05-26 13:42 UTCEPSS rescoreEPSS 94% · 99th percentile
Public detection templates
(1 reference)A public Nuclei detection template is referenced for this CVE. A detection template checks whether a system is affected; it is not necessarily exploit code.
- Nucleihttp/cves/2020/CVE-2020-26258.yamlPublished Mar 29, 2023
XStream <1.4.15 - Server-Side Request Forgery
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-2020-26217NVD 8.8EG 9.0EPSS p100CRITICAL
- CVE-2020-26259NVD 6.8EG 8.9EPSS p100HIGH
- CVE-2021-39139EG 8.8EPSS p92HIGH
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Same vendor
10 shownredhat:RHSA-2021:2139
- CVE-2020-26259NVD 6.8EG 8.9EPSS p100HIGH
- CVE-2021-21345EG 9.9EPSS p99CRITICAL
- CVE-2021-21350EG 9.8EPSS p97CRITICAL
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- CVE-2021-21346EG 9.8EPSS p100CRITICAL
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- CVE-2021-21342EG 9.1EPSS p99CRITICAL
- CVE-2021-21341NVD 7.5EG 8.8EPSS p100HIGH
- CVE-2021-21349EG 8.7EPSS p99HIGH
Same CWE
10 shownCWE-918
- CVE-2020-10770NVD 5.3EG 8.0EPSS p99HIGH
- CVE-2020-17513EG 5.3EPSS p91MEDIUM
- CVE-2020-8464EG 7.5EPSS p94HIGH
- CVE-2020-24444EG 5.8MEDIUM
- CVE-2020-35712EG 9.8CRITICAL
- CVE-2020-26032EG 7.5HIGH
- CVE-2020-35850EG 6.5MEDIUM
- CVE-2020-28735EG 8.8HIGH
- CVE-2020-28978EG 5.3EPSS p97MEDIUM
- CVE-2020-28977EG 5.3EPSS p97MEDIUM
Frequently asked(5)
What is CVE-2020-26258?
When was the CVE record for CVE-2020-26258 published?
Is CVE-2020-26258 actively exploited?
What is the CVSS score of CVE-2020-26258?
How do I remediate CVE-2020-26258?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2020-26258
Is Your Infrastructure Affected by CVE-2020-26258?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.