CVE-2021-29505

CRITICALNVD 8.89.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because EPSS predicts 77% probability of exploitation within the next 30 days (99th percentile of EPSS-scored CVEs). NVD baseline CVSS 8.8 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction (continuous uplift above 30%)
Sources: epss, nvd
Trending — 4 sources updated this weekElevated
9.0EG
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 77%
CISA-KEV: Not listedEPSS PROB: 77%CVSS: 8.8Exploit: Elevated riskExposed services: Not assessed

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
8.8
EG Score
9.0CRITICALhigh confidence
EG Risk
71
EG Risk 71/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity90% × 45%
Exploitation77% × 40%
Automatability0% × 15%
CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
77%
EPSS %ILE
99th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

May 28, 2021

Last Modified

October 7, 2026

Advisory Details (10)

Auto-updated Oct 7, 2026
Patch available. Sources: github, github_commit.
generic

[SECURITY] [DSA 5004-1] libxstream-java security update

https://www.debian.org/security/2021/dsa-5004
generic

NetApp Product Security

https://security.netapp.com/advisory/ntap-20210708-0007
generic

[SECURITY] Fedora 34 Update: xstream-1.4.18-2.fc34 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/[email protected]/message/QGXIU3YDPG6OGTDHMBLAFN7BPBERXREB
generic

[SECURITY] Fedora 35 Update: xstream-1.4.18-2.fc35 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/[email protected]/message/PVPHZA7VW2RRSDCOIPP2W6O5ND254TU7
generic

[SECURITY] Fedora 33 Update: xstream-1.4.18-2.fc33 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/[email protected]/message/22KVR6B5IZP3BGQ3HPWIO2FWWCKT3DHP
genericMentions a patch (unverified)

[SECURITY] [DLA 2704-1] libxstream-java security update

https://lists.debian.org/debian-lts-announce/2021/07/msg00004.html
generic

Pony Mail

https://lists.apache.org/thread.html/r8ee51debf7fd184b6a6b020dc31df25118b0aa612885f12fbe77f04f@%3Cdev.jmeter.apache.org%3E
github_commit

commit f0c4a8d861b6 (x-stream/xstream)

Fix landed in x-stream/xstream commit f0c4a8d861b6 — awaiting tagged release

https://github.com/x-stream/xstream/commit/f0c4a8d861b68ffc3119cfbbbd632deee624e227
github_commit

commit 24fac8219129 (x-stream/xstream)

Fix landed in x-stream/xstream commit 24fac8219129 — awaiting tagged release

https://github.com/x-stream/xstream/commit/24fac82191292c6ae25f94508d28b9823f83624f
githubMentions a patch (unverified)

XStream is vulnerable to a Remote Command Execution attack · Advisory · x-stream/xstream · GitHub

https://github.com/x-stream/xstream/security/advisories/GHSA-7chv-rrw6-w6fc

Vendor Advisories for CVE-2021-29505(6)

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 / EcosystemFix (by version range) / 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

(6 across 6 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
libxstream-java—
  • every version up to 1.4.15-3: fixed in 1.4.15-3
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
libxstream-java—
  • every version up to 1.4.15-3: fixed in 1.4.15-3
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
libxstream-java—
  • every version up to 1.4.15-3: fixed in 1.4.15-3
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
libxstream-java—
  • every version up to 1.4.15-3: fixed in 1.4.15-3
—
Debian:9(1)
PackageVulnerable rangeFix by version rangeDependents
libxstream-java1.4.10-1 ... 1.4.9-2+deb9u1 (7 versions)
  • every version up to 1.4.11.1-1+deb9u3: fixed in 1.4.11.1-1+deb9u3
—
Maven(1)
PackageVulnerable rangeFix by version rangeDependents
com.thoughtworks.xstream:xstream0.1 ... 1.4.9 (41 versions)
  • every version up to 1.4.17: fixed in 1.4.17
—

Weakness Classification(2)

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

Additional Vendor Advisories

(1)

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 9× in last 7d / 24× 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.

Showing the most recent 100 of 107 total refreshes for this CVE.

  1. 2026-10-07 23:44 UTCEPSS rescore
  2. 2026-10-07 21:46 UTCEG score recompute▲ 0.20
  3. 2026-10-07 21:46 UTCVendor advisory
  4. 2026-10-07 21:23 UTCNVD updateCVSS v3 → 8.8
  5. 2026-10-07 20:46 UTCEG score recompute
  6. 2026-10-07 20:46 UTCVendor advisory
  7. 2026-10-06 15:14 UTCEPSS rescore
  8. 2026-10-03 14:22 UTCEPSS rescore
  9. 2026-10-03 14:22 UTCEPSS rescore
  10. 2026-10-02 16:22 UTCEPSS rescore
  11. 2026-09-30 15:34 UTCEG score recompute
  12. 2026-09-30 15:00 UTCEPSS rescore
  13. 2026-09-28 13:47 UTCEPSS rescore
  14. 2026-09-26 15:54 UTCEPSS rescore
  15. 2026-09-26 15:54 UTCEPSS rescore
  16. 2026-09-26 01:15 UTCOSV refresh
  17. 2026-09-24 14:00 UTCEPSS rescore
  18. 2026-09-21 20:28 UTCEPSS rescore
  19. 2026-09-18 19:23 UTCEPSS rescore
  20. 2026-09-17 19:23 UTCEPSS rescore
  21. 2026-09-17 19:23 UTCEPSS rescore
  22. 2026-09-16 14:05 UTCEPSS rescore
  23. 2026-09-13 16:43 UTCEPSS rescore
  24. 2026-09-12 14:57 UTCEPSS rescore
  25. 2026-09-06 16:31 UTCOSV refresh
Show 75 more
  1. 2026-09-06 13:44 UTCEPSS rescore
  2. 2026-09-05 15:25 UTCEPSS rescore
  3. 2026-09-04 13:57 UTCEPSS rescore
  4. 2026-09-01 13:50 UTCEPSS rescore
  5. 2026-08-30 19:14 UTCEPSS rescore
  6. 2026-08-30 01:19 UTCEPSS rescore
  7. 2026-08-28 21:37 UTCEPSS rescore
  8. 2026-08-26 14:42 UTCEPSS rescore
  9. 2026-08-25 13:45 UTCEPSS rescore
  10. 2026-08-24 14:12 UTCEPSS rescore
  11. 2026-08-21 23:46 UTCEPSS rescore
  12. 2026-08-20 22:52 UTCEPSS rescore
  13. 2026-08-20 02:15 UTCOSV refresh
  14. 2026-08-19 17:01 UTCEPSS rescore
  15. 2026-08-18 13:45 UTCEPSS rescore
  16. 2026-08-17 13:44 UTCEPSS rescore
  17. 2026-08-16 14:53 UTCEPSS rescore
  18. 2026-08-16 02:11 UTCEPSS rescore
  19. 2026-08-16 02:11 UTCEPSS rescore
  20. 2026-08-15 01:27 UTCEPSS rescore
  21. 2026-08-13 21:57 UTCEPSS rescore
  22. 2026-08-12 13:47 UTCEPSS rescore
  23. 2026-08-11 13:38 UTCEPSS rescore
  24. 2026-08-07 16:23 UTCEPSS rescore
  25. 2026-08-05 19:14 UTCEPSS rescore
  26. 2026-08-04 21:27 UTCOSV refresh
  27. 2026-07-30 16:25 UTCEPSS rescore
  28. 2026-07-30 16:25 UTCEPSS rescore
  29. 2026-07-28 15:33 UTCEPSS rescore
  30. 2026-07-26 14:52 UTCEPSS rescore
  31. 2026-07-26 14:52 UTCEPSS rescore
  32. 2026-07-24 14:15 UTCEPSS rescore
  33. 2026-07-23 14:16 UTCEPSS rescore
  34. 2026-07-23 01:59 UTCEG score recompute▲ 1.30
  35. 2026-07-22 22:46 UTCEG score recompute▼ 1.50
  36. 2026-07-22 14:06 UTCEPSS rescore
  37. 2026-07-22 14:06 UTCEPSS rescore
  38. 2026-07-21 15:22 UTCEPSS rescore
  39. 2026-07-21 15:22 UTCEPSS rescore
  40. 2026-07-20 17:05 UTCEPSS rescore
  41. 2026-07-18 19:29 UTCOSV refresh
  42. 2026-07-15 16:55 UTCEPSS rescore
  43. 2026-07-15 16:55 UTCEPSS rescore
  44. 2026-07-13 22:27 UTCEPSS rescore
  45. 2026-07-13 22:27 UTCEPSS rescore
  46. 2026-07-11 08:25 UTCEPSS rescore
  47. 2026-07-11 08:25 UTCEPSS rescore
  48. 2026-07-08 15:12 UTCEPSS rescore
  49. 2026-07-04 06:29 UTCEPSS rescore
  50. 2026-07-04 06:29 UTCEPSS rescore
  51. 2026-07-02 16:57 UTCEPSS rescore
  52. 2026-07-01 02:18 UTCOSV refresh
  53. 2026-06-30 23:20 UTCEPSS rescore
  54. 2026-06-30 23:20 UTCEPSS rescore
  55. 2026-06-29 14:04 UTCEPSS rescore
  56. 2026-06-28 04:54 UTCEPSS rescore
  57. 2026-06-28 04:54 UTCEPSS rescore
  58. 2026-06-25 13:48 UTCEPSS rescore
  59. 2026-06-25 13:48 UTCEPSS rescore
  60. 2026-06-23 21:31 UTCEPSS rescore
  61. 2026-06-23 21:31 UTCEPSS rescore
  62. 2026-06-21 14:55 UTCEPSS rescore
  63. 2026-06-21 14:54 UTCEPSS rescore
  64. 2026-06-21 01:58 UTCEPSS rescore
  65. 2026-06-21 01:58 UTCEPSS rescore
  66. 2026-06-18 17:51 UTCEPSS rescore
  67. 2026-06-18 17:51 UTCEPSS rescore
  68. 2026-06-16 17:51 UTCEPSS rescore
  69. 2026-06-15 17:46 UTCEPSS rescore
  70. 2026-06-13 22:58 UTCEPSS rescore
  71. 2026-06-13 22:58 UTCEPSS rescore
  72. 2026-06-13 04:43 UTCOSV refresh
  73. 2026-06-10 22:16 UTCEPSS rescore
  74. 2026-06-10 13:20 UTCEPSS rescore
  75. 2026-06-08 14:15 UTCEPSS rescore

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 product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2021-29505?
CVE-2021-29505 is a critical 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 on May 28, 2021, with the most recent update on October 7, 2026. 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 77% probability of exploitation in the next 30 days (99th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2021-29505?
CVE-2021-29505 has a CVSS v3 base score of 8.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0 (CRITICAL).
How do I remediate CVE-2021-29505?
A fix for CVE-2021-29505 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2021-29505 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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