CVE-2026-274598.1HighCWE-120

CVE-2026-27459: pyOpenSSL DTLS cookie callback buffer overflow

pyca · pyopenssl

Vendor fix available · Affected: pyca pyopenssl · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.8%probability of exploitation in the next 30 days

57th percentile

050100

Higher than 57% of scored CVEs

8.1HighCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 22.0.0 and prior to version 26.0.0, if a user provided callback to `set_cookie_generate_callback` returned a cookie value greater than 256 bytes, pyOpenSSL would overflow an OpenSSL provided buffer. Starting in version 26.0.0, cookie values that are too long are now rejected.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

pyca · pyopenssl>= 22.0.0, < 26.0.0

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Classic Buffer Overflow · Memory Corruption
Vendor: pyca
Published: March 2026
Band: Unlikely (under 1%), March 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-27459 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.

References

14 more references are in the CVE record.