CVE-2021-25122

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 18.1%, top 3% of all CVEs by exploit prediction. 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: epss, nvd
Elevated
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 18%CVSS: 7.5Exploit: Elevated riskExposed: 0

A fix is available — apply it.

When responding to new h2c connection requests, Apache Tomcat versions 10.0.0-M1 to 10.0.0, 9.0.0.M1 to 9.0.41 and 8.5.0 to 8.5.61 could duplicate request headers and a limited amount of request body from one request to another meaning user A and user B could both see the results of user A's request.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
54(Track)
EG Risk 54/100SSVC: Track

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
Severity75% × 45%
Exploitation40% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
18%
EPSS %ILE
97%
KEV
Not listed

Published

March 1, 2021

Last Modified

August 25, 2026

Advisory Details (7)

Auto-updated Aug 25, 2026
No patch confirmed yet.
generic
https://lists.apache.org/thread.html/rd0463f9a5cbc02a485404c4b990f0da452e5ac5c237808edba11c947%40%3Cusers.tomcat.apache.org%3E
generic
https://lists.apache.org/thread.html/rcd90bf36b1877e1310b87ecd14ed7bbb15da52b297efd9f0e7253a3b%40%3Cusers.tomcat.apache.org%3E
generic
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cusers.tomcat.apache.org%3E
generic
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cdev.tomcat.apache.org%3E
generic
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E
generic
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.apache.org%3E
generic

oss-security - CVE-2021-25122: Apache Tomcat h2c request mix-up

http://www.openwall.com/lists/oss-security/2021/03/01/1

Vendor Advisories for CVE-2021-25122(3)

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

Patch Availability(4)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntutomcat8-user (8.0.32-1ubuntu1.13+esm1) @ xenial2026-08-25ubuntu
ubuntutomcat9-examples (9.0.31-1ubuntu0.2) @ focal2026-08-25ubuntu
redhattomcat2022-07-07redhat
redhatjws5-tomcat-vault-0:1.1.8-2.Final_redhat_00003.1.el8jws2021-06-29redhat

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

(8 across 7 ecosystems)
Maven(2)
PackageVulnerable rangeFixed inDependents
org.apache.tomcat.embed:tomcat-embed-core8.5.0 ... 8.5.9 (50 versions)8.5.63—
org.apache.tomcat:tomcat-coyote10.0.0 ... 10.0.0-M9 (10 versions)10.0.2—
Debian:10(1)
PackageVulnerable rangeFixed inDependents
tomcat99.0.16-4 ... 9.0.31-1~deb10u3 (9 versions)9.0.31-1~deb10u4—
Debian:11(1)
PackageVulnerable rangeFixed inDependents
tomcat9—9.0.43-1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
tomcat9—9.0.43-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
tomcat9—9.0.43-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
tomcat9—9.0.43-1—
Debian:9(1)
PackageVulnerable rangeFixed inDependents
tomcat88.5.14-1 ... 8.5.54-0+deb9u5 (42 versions)8.5.54-0+deb9u6—

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 8× in last 7d / 33× 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 152 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2021-25122?
CVE-2021-25122 is a high vulnerability published on March 1, 2021. When responding to new h2c connection requests, Apache Tomcat versions 10.0.0-M1 to 10.0.0, 9.0.0.M1 to 9.0.41 and 8.5.0 to 8.5.61 could duplicate request headers and a limited amount of request body from one request to another meaning user A and user B could both see the results of user A's…
When was CVE-2021-25122 disclosed?
CVE-2021-25122 was first published in the National Vulnerability Database on March 1, 2021, with the most recent update on August 25, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-25122 actively exploited?
CVE-2021-25122 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 18% probability of exploitation in the next 30 days, which ranks it in the top 2.9% of all scored CVEs.
What is the CVSS score of CVE-2021-25122?
CVE-2021-25122 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2021-25122?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-25122, 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-2021-25122

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