CVE-2020-17527

HIGHNVD 7.57.5
EchelonGraph scoreLOW confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). 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: nvd
Elevated
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 25%CVSS: 7.5Exploit: NoneExposed: 0

A fix is available — apply it.

While investigating bug 64830 it was discovered that Apache Tomcat 10.0.0-M1 to 10.0.0-M9, 9.0.0-M1 to 9.0.39 and 8.5.0 to 8.5.59 could re-use an HTTP request header value from the previous stream received on an HTTP/2 connection for the request associated with the subsequent stream. While this would most likely lead to an error and the closure of the HTTP/2 connection, it is possible that information could leak between requests.

CVSS v3
7.5
EG Score
7.5(low)
EPSS
97.6%
KEV
Not listed

Published

December 3, 2020

Last Modified

November 21, 2024

References (50)

Vendor Advisories for CVE-2020-17527(1)

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
ubuntutomcat9-examples (9.0.31-1ubuntu0.2) @ focal2026-05-23ubuntu
redhattomcat2021-12-14redhat
redhatjws5-tomcat-native-0:1.2.25-3.redhat_3.el8jws2021-02-11redhat

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
org.apache.tomcat:tomcat-coyote8.5.0 ... 8.5.9 (48 versions)8.5.60—

Weakness Classification(1)

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 9× in last 7d / 38× 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. 2026-07-09 19:07 UTCEPSS rescore
  4. 2026-07-08 15:12 UTCEPSS rescore
  5. 2026-07-07 13:43 UTCEPSS rescore
  6. 2026-07-07 13:43 UTCEPSS rescore
  7. 2026-07-06 16:25 UTCEPSS rescore
  8. 2026-07-06 16:25 UTCEPSS rescore
  9. 2026-07-05 02:27 UTCEPSS rescore
  10. 2026-07-04 06:29 UTCEPSS rescore
  11. 2026-07-04 06:28 UTCEPSS rescore
  12. 2026-07-01 15:03 UTCEPSS rescore
  13. 2026-06-29 14:04 UTCEPSS rescore
  14. 2026-06-28 14:05 UTCEPSS rescore
  15. 2026-06-28 04:54 UTCEPSS rescore
  16. 2026-06-28 04:54 UTCEPSS rescore
  17. 2026-06-27 03:06 UTCEPSS rescore
  18. 2026-06-25 13:47 UTCEPSS rescore
  19. 2026-06-24 14:03 UTCEPSS rescore
  20. 2026-06-24 14:03 UTCEPSS rescore
  21. 2026-06-24 08:20 UTCOSV refresh
  22. 2026-06-23 21:31 UTCEPSS rescore
  23. 2026-06-23 21:31 UTCEPSS rescore
  24. 2026-06-22 14:23 UTCEPSS rescore
  25. 2026-06-22 14:23 UTCEPSS rescore
Show 45 more
  1. 2026-06-21 14:54 UTCEPSS rescore
  2. 2026-06-21 14:54 UTCEPSS rescore
  3. 2026-06-21 01:57 UTCEPSS rescore
  4. 2026-06-21 01:57 UTCEPSS rescore
  5. 2026-06-18 17:50 UTCEPSS rescore
  6. 2026-06-17 17:50 UTCEPSS rescore
  7. 2026-06-16 17:50 UTCEPSS rescore
  8. 2026-06-16 17:50 UTCEPSS rescore
  9. 2026-06-15 17:46 UTCEPSS rescore
  10. 2026-06-14 23:15 UTCEPSS rescore
  11. 2026-06-13 22:58 UTCEPSS rescore
  12. 2026-06-13 22:58 UTCEPSS rescore
  13. 2026-06-12 23:10 UTCEPSS rescore
  14. 2026-06-11 13:58 UTCEPSS rescore
  15. 2026-06-10 22:16 UTCEPSS rescore
  16. 2026-06-10 22:16 UTCEPSS rescore
  17. 2026-06-10 13:20 UTCEPSS rescore
  18. 2026-06-07 15:23 UTCEPSS rescore
  19. 2026-06-07 15:23 UTCEPSS rescore
  20. 2026-06-07 11:59 UTCOSV refresh
  21. 2026-06-06 13:45 UTCEPSS rescore
  22. 2026-06-06 13:45 UTCEPSS rescore
  23. 2026-06-05 22:45 UTCEPSS rescore
  24. 2026-06-05 22:45 UTCEPSS rescore
  25. 2026-06-05 06:08 UTCEPSS rescore
  26. 2026-06-05 06:08 UTCEPSS rescore
  27. 2026-06-04 13:10 UTCEPSS rescore
  28. 2026-06-04 13:10 UTCEPSS rescore
  29. 2026-06-02 20:11 UTCEPSS rescore
  30. 2026-06-02 20:11 UTCEPSS rescore
  31. 2026-05-31 22:29 UTCEPSS rescore
  32. 2026-05-31 22:29 UTCEPSS rescore
  33. 2026-05-31 00:15 UTCEPSS rescore
  34. 2026-05-31 00:15 UTCEPSS rescore
  35. 2026-05-29 13:42 UTCEPSS rescore
  36. 2026-05-28 13:43 UTCEPSS rescore
  37. 2026-05-28 13:43 UTCEPSS rescore
  38. 2026-05-27 13:39 UTCEPSS rescore
  39. 2026-05-26 13:42 UTCEPSS rescore
  40. 2026-05-26 13:42 UTCEPSS rescore
  41. 2026-05-26 07:17 UTCEPSS rescore
  42. 2026-05-26 07:17 UTCEPSS rescore
  43. 2026-05-24 16:48 UTCEPSS rescore
  44. 2026-05-23 04:41 UTCEG score recompute
  45. 2026-05-23 04:41 UTCVendor advisory

Publicly available exploits

(1 reference)

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 PoCforse01/CVE-2020-17527-Tomcat
    First seen Feb 5, 2021
    Open source ↗

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2020-17527?
CVE-2020-17527 is a high vulnerability published on December 3, 2020. While investigating bug 64830 it was discovered that Apache Tomcat 10.0.0-M1 to 10.0.0-M9, 9.0.0-M1 to 9.0.39 and 8.5.0 to 8.5.59 could re-use an HTTP request header value from the previous stream received on an HTTP/2 connection for the request associated with the subsequent stream. While this…
When was CVE-2020-17527 disclosed?
CVE-2020-17527 was first published in the National Vulnerability Database on December 3, 2020, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2020-17527 actively exploited?
CVE-2020-17527 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 97.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2020-17527?
CVE-2020-17527 has a CVSS v3 base score of 7.5 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2020-17527?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-17527, 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-2020-17527

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