CVE-2021-29505

HIGHNVD 7.59.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because EPSS predicts 90% probability of exploitation within the next 30 days (top 0.4% of all CVEs). NVD baseline CVSS 7.5 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction ≥85%
Sources: epss, nvd
Elevated
7.5
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 78%
CISA-KEV: Not listedEPSS: 78%CVSS: 7.5Exploit: NoneExposed: 0

A fix is available — apply it.

XStream is software for serializing Java objects to XML and back again. A vulnerability in XStream versions prior to 1.4.17 may allow a remote attacker has sufficient rights to execute commands of the host only by manipulating the processed input stream. No user who followed the recommendation to setup XStream's security framework with a whitelist limited to the minimal required types is affected. The vulnerability is patched in version 1.4.17.

CVSS v3
7.5
EG Score
9.0(high)
EPSS
99.5%
KEV
Not listed

Published

May 28, 2021

Last Modified

May 30, 2025

References (28)

Vendor Advisories for CVE-2021-29505(2)

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

Patch Availability(3)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatxstream2022-07-07redhat
redhatpatch2021-11-23redhat
redhatxstream-0:1.3.1-14.el7_92021-07-12redhat

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 (41 versions)1.4.17—

Weakness Classification(2)

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

Additional Vendor Advisories

(5)

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 3× in last 7d / 27× 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. 2026-07-11 08:25 UTCEPSS rescore
  2. 2026-07-11 08:25 UTCEPSS rescore
  3. 2026-07-08 15:12 UTCEPSS rescore
  4. 2026-07-04 06:29 UTCEPSS rescore
  5. 2026-07-04 06:29 UTCEPSS rescore
  6. 2026-07-02 16:57 UTCEPSS rescore
  7. 2026-07-01 02:18 UTCOSV refresh
  8. 2026-06-30 23:20 UTCEPSS rescore
  9. 2026-06-30 23:20 UTCEPSS rescore
  10. 2026-06-29 14:04 UTCEPSS rescore
  11. 2026-06-28 04:54 UTCEPSS rescore
  12. 2026-06-28 04:54 UTCEPSS rescore
  13. 2026-06-25 13:48 UTCEPSS rescore
  14. 2026-06-25 13:48 UTCEPSS rescore
  15. 2026-06-23 21:31 UTCEPSS rescore
  16. 2026-06-23 21:31 UTCEPSS rescore
  17. 2026-06-21 14:55 UTCEPSS rescore
  18. 2026-06-21 14:54 UTCEPSS rescore
  19. 2026-06-21 01:58 UTCEPSS rescore
  20. 2026-06-21 01:58 UTCEPSS rescore
  21. 2026-06-18 17:51 UTCEPSS rescore
  22. 2026-06-18 17:51 UTCEPSS rescore
  23. 2026-06-16 17:51 UTCEPSS rescore
  24. 2026-06-15 17:46 UTCEPSS rescore
  25. 2026-06-13 22:58 UTCEPSS rescore
Show 12 more
  1. 2026-06-13 22:58 UTCEPSS rescore
  2. 2026-06-13 04:43 UTCOSV refresh
  3. 2026-06-10 22:16 UTCEPSS rescore
  4. 2026-06-10 13:20 UTCEPSS rescore
  5. 2026-06-08 14:15 UTCEPSS rescore
  6. 2026-06-04 13:10 UTCEPSS rescore
  7. 2026-06-04 13:10 UTCEPSS rescore
  8. 2026-05-31 00:15 UTCEPSS rescore
  9. 2026-05-28 13:43 UTCEPSS rescore
  10. 2026-05-28 13:43 UTCEPSS rescore
  11. 2026-05-26 15:52 UTCEG score recompute
  12. 2026-05-26 15:52 UTCVendor advisory

Publicly available exploits

(2 references)

Working exploit code is in the public domain (1 GitHub PoC). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCMyBlackManba/CVE-2021-29505
    First seen Jun 8, 2021

    对CVE-2021-29505进行复现，并分析学了下Xstream反序列化过程

    Open source ↗
  • Nucleihttp/cves/2021/CVE-2021-29505.yaml
    First seen Jan 1, 2021

    XStream <1.4.17 - Remote Code Execution

    Open source ↗

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2021-29505?
CVE-2021-29505 is a high vulnerability published on May 28, 2021. XStream is software for serializing Java objects to XML and back again. A vulnerability in XStream versions prior to 1.4.17 may allow a remote attacker has sufficient rights to execute commands of the host only by manipulating the processed input stream. No user who followed the recommendation to…
When was CVE-2021-29505 disclosed?
CVE-2021-29505 was first published in the National Vulnerability Database on May 28, 2021, with the most recent update on May 30, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-29505 actively exploited?
CVE-2021-29505 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 99.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-29505?
CVE-2021-29505 has a CVSS v3 base score of 7.5 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
How do I remediate CVE-2021-29505?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-29505, 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-2021-29505

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