CVE-2026-3298

HIGHPre-NVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 68% 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, secondary
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.8Exploit: None knownExposed: 0

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

The method "sock_recvfrom_into()" of "asyncio.ProacterEventLoop" (Windows only) was missing a boundary check for the data buffer when using nbytes parameter. This allowed for an out-of-bounds buffer write if data was larger than the buffer size. Non-Windows platforms are not affected.

CVSS v3
8.8
EG Score
8.8(medium)
EG Risk
40(Track)
EG Risk 40/100SSVC: 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
Severity88% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
33%
KEV
Not listed

Published

April 21, 2026

Last Modified

August 13, 2026

Advisory Details (6)

Auto-updated May 2, 2026
No patch confirmed yet.
generic

Mailman 3 [CVE-2026-3298] Out-of-bounds write in Windows asyncio.ProacterEventLoop.sock_recvfrom_into() when using nbytes - Security-announce - python.org

https://mail.python.org/archives/list/[email protected]/thread/KWTPIQBOOOUNQP7UFSLBI437NJDFLA3F/
generic

gh-148808: Add boundary check to asyncio.AbstractEventLoop.sock_recvf… by sethmlarson · Pull Request #148809 · python/cpython · GitHub

https://github.com/python/cpython/pull/148809
generic

asyncio.AbstractEventLoop.sock_recvfrom_into() on Windows doesn't check buffer length · Issue #148808 · python/cpython · GitHub

https://github.com/python/cpython/issues/148808
generic

[3.13] gh-148808: Add boundary check to asyncio.AbstractEventLoop.soc… · python/cpython@95633d2 · GitHub

https://github.com/python/cpython/commit/95633d2aad4721e25e4dfd9f43dfb6e1edcbd741
generic

[3.14] gh-148808: Add boundary check to asyncio.AbstractEventLoop.soc… · python/cpython@27522b7 · GitHub

https://github.com/python/cpython/commit/27522b7d6e6588f03e61099dd858cd5a9314e2f2
generic

gh-148808: Add boundary check to asyncio.AbstractEventLoop.sock_recvf… · python/cpython@1274766 · GitHub

https://github.com/python/cpython/commit/1274766d3c29007ab77245a72abbf8dce2a9db4d

Vendor Advisories for CVE-2026-3298(2)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× 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.

Showing the most recent 100 of 208 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-3298?
CVE-2026-3298 is a high vulnerability published on April 21, 2026. The method "sockrecvfrominto()" of "asyncio.ProacterEventLoop" (Windows only) was missing a boundary check for the data buffer when using nbytes parameter. This allowed for an out-of-bounds buffer write if data was larger than the buffer size. Non-Windows platforms are not affected.
When was CVE-2026-3298 disclosed?
CVE-2026-3298 was first published in the National Vulnerability Database on April 21, 2026, with the most recent update on August 13, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-3298 actively exploited?
CVE-2026-3298 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 67.3% of all scored CVEs.
What is the CVSS score of CVE-2026-3298?
CVE-2026-3298 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2026-3298?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-3298, 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.

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