CVE-2021-42697

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 75.5%, top 1% 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
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 36%CVSS: 7.5Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Akka HTTP 10.1.x before 10.1.15 and 10.2.x before 10.2.7 can encounter stack exhaustion while parsing HTTP headers, which allows a remote attacker to conduct a Denial of Service attack by sending a User-Agent header with deeply nested comments.

CVSS v3
7.5
EG Score
7.5(medium)
EPSS
98.3%
KEV
Not listed

Published

November 2, 2021

Last Modified

November 21, 2024

References (10)

Affected Packages

(7 across 1 ecosystem)
Maven(7)
PackageVulnerable rangeFixed inDependents
com.typesafe.akka:aakka-http-core_2.13.0-M3———
com.typesafe.akka:akka-http-core_2.1110.1.0 ... 10.1.9 (15 versions)10.1.15—
com.typesafe.akka:akka-http-core_2.1210.2.0 ... 10.2.6 (12 versions)10.2.7—
com.typesafe.akka:akka-http-core_2.1310.2.0 ... 10.2.6 (12 versions)10.2.7—
com.typesafe.akka:akka-http-core_2.13.0-M510.1.7, 10.1.8——
com.typesafe.akka:akka-http-core_2.13.0-RC210.1.8——
com.typesafe.akka:akka-http-core_2.13.0-RC310.1.8——

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 6× in last 7d / 39× 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. 2026-07-07 13:43 UTCEPSS rescore
  5. 2026-07-06 02:21 UTCEPSS rescore
  6. 2026-07-06 02:21 UTCEPSS rescore
  7. 2026-07-05 02:28 UTCEPSS rescore
  8. 2026-07-05 02:28 UTCEPSS rescore
  9. 2026-07-02 16:57 UTCEPSS rescore
  10. 2026-07-01 15:04 UTCEPSS rescore
  11. 2026-06-30 08:00 UTCOSV refresh
  12. 2026-06-28 04:54 UTCEPSS rescore
  13. 2026-06-28 04:54 UTCEPSS rescore
  14. 2026-06-27 03:06 UTCEPSS rescore
  15. 2026-06-27 03:06 UTCEPSS rescore
  16. 2026-06-25 13:48 UTCEPSS rescore
  17. 2026-06-25 13:48 UTCEPSS rescore
  18. 2026-06-24 14:03 UTCEPSS rescore
  19. 2026-06-24 14:03 UTCEPSS rescore
  20. 2026-06-23 21:31 UTCEPSS rescore
  21. 2026-06-23 21:31 UTCEPSS rescore
  22. 2026-06-21 01:58 UTCEPSS rescore
  23. 2026-06-21 01:58 UTCEPSS rescore
  24. 2026-06-19 19:24 UTCEPSS rescore
  25. 2026-06-19 19:24 UTCEPSS rescore
Show 42 more
  1. 2026-06-18 17:51 UTCEPSS rescore
  2. 2026-06-18 17:51 UTCEPSS rescore
  3. 2026-06-17 17:51 UTCEPSS rescore
  4. 2026-06-17 17:51 UTCEPSS rescore
  5. 2026-06-17 17:51 UTCEPSS rescore
  6. 2026-06-16 17:51 UTCEPSS rescore
  7. 2026-06-16 17:51 UTCEPSS rescore
  8. 2026-06-15 17:46 UTCEPSS rescore
  9. 2026-06-14 23:15 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. 2026-06-12 17:40 UTCOSV refresh
  15. 2026-06-11 13:58 UTCEPSS rescore
  16. 2026-06-11 13:58 UTCEPSS rescore
  17. 2026-06-10 22:16 UTCEPSS rescore
  18. 2026-06-10 22:16 UTCEPSS rescore
  19. 2026-06-10 13:20 UTCEPSS rescore
  20. 2026-06-08 14:15 UTCEPSS rescore
  21. 2026-06-08 14:15 UTCEPSS rescore
  22. 2026-06-07 15:23 UTCEPSS rescore
  23. 2026-06-07 15:23 UTCEPSS rescore
  24. 2026-06-06 13:46 UTCEPSS rescore
  25. 2026-06-06 13:46 UTCEPSS rescore
  26. 2026-06-05 22:45 UTCEPSS rescore
  27. 2026-06-05 06:09 UTCEPSS rescore
  28. 2026-06-05 06:09 UTCEPSS rescore
  29. 2026-06-02 20:11 UTCEPSS rescore
  30. 2026-06-02 20:11 UTCEPSS rescore
  31. 2026-06-01 13:50 UTCEPSS rescore
  32. 2026-06-01 13:50 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. 2026-05-26 08:09 UTCEG score recompute
  39. 2026-05-26 07:17 UTCEPSS rescore
  40. 2026-05-26 07:17 UTCEPSS rescore
  41. 2026-05-26 07:17 UTCEPSS rescore
  42. 2026-05-26 04:16 UTCOSV refresh

Publicly available exploits

(1 reference)

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

  • Exploit-DBEDB-50892
    First seen May 11, 2022

    Akka HTTP 10.1.14 - Denial of Service

    Open source ↗

Frequently asked(5)

What is CVE-2021-42697?
CVE-2021-42697 is a high vulnerability published on November 2, 2021. Akka HTTP 10.1.x before 10.1.15 and 10.2.x before 10.2.7 can encounter stack exhaustion while parsing HTTP headers, which allows a remote attacker to conduct a Denial of Service attack by sending a User-Agent header with deeply nested comments.
When was CVE-2021-42697 disclosed?
CVE-2021-42697 was first published in the National Vulnerability Database on November 2, 2021, 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-2021-42697 actively exploited?
CVE-2021-42697 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 98.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-42697?
CVE-2021-42697 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2021-42697?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-42697, 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

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