CVE-2026-3298
CVE-2026-3298 is a high-severity vulnerability with a CVSS 4.0 base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.
Key facts
- Severity: High (CVSS 4.0 base score 8.8)
- EPSS exploit prediction: 0% (29th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-24136
- Weakness: CWE-787
- Published:
- Last modified:
Description
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.
Frequently asked questions
- What is CVE-2026-3298?
- 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.
- How severe is CVE-2026-3298?
- CVE-2026-3298 has a CVSS 4.0 base score of 8.8, rated high severity.
- Is CVE-2026-3298 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (29th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-3298?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-3298 have an EU (EUVD) identifier?
- Yes. CVE-2026-3298 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-24136.
- When was CVE-2026-3298 published?
- CVE-2026-3298 was published on 2026-04-21 and last updated on 2026-06-17.
References
- https://github.com/python/cpython/commit/1274766d3c29007ab77245a72abbf8dce2a9db4d
- https://github.com/python/cpython/commit/27522b7d6e6588f03e61099dd858cd5a9314e2f2
- https://github.com/python/cpython/commit/95633d2aad4721e25e4dfd9f43dfb6e1edcbd741
- https://github.com/python/cpython/issues/148808
- https://github.com/python/cpython/pull/148809
- https://mail.python.org/archives/list/[email protected]/thread/KWTPIQBOOOUNQP7UFSLBI437NJDFLA3F/
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