Is CVE-2026-39834 in the CISA KEV catalog?

No. CVE-2026-39834 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-39834?

CVE-2026-39834 has a CVSS v3 base score of 9.1 (Important).

What is the EPSS score for CVE-2026-39834?

CVE-2026-39834 has an EPSS score of 0.47% (37th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2026-39834

HIGH

9.1

CVSS v3

NVD

Description

When writing data larger than 4GB in a single Write call on an SSH channel, an integer overflow in the internal payload size calculation caused the write loop to spin indefinitely, sending empty packets without making progress. The size comparison now uses int64 to prevent truncation.

CWE-190Integer Overflow

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H/E:U

Exploit Intelligence

0.47%probability of exploitation in 30 days

37thpercentile

Low risk: more likely to be exploited than 37% of all known CVEs.

References

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-28.