How severe is CVE-2015-3963?

CVE-2015-3963 has a CVSS 2.0 base score of 5.8, rated medium severity.

Is CVE-2015-3963 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (89th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2015-3963?

CVE-2015-3963 primarily affects Windriver Vxworks. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2015-3963?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2015-3963 published?

CVE-2015-3963 was published on 2015-08-04 and last updated on 2026-06-17.

CVE-2015-3963

CVE-2015-3963 is a medium-severity vulnerability in Windriver Vxworks with a CVSS 2.0 base score of 5.8. 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-330.

Key facts

Severity: Medium (CVSS 2.0 base score 5.8)
EPSS exploit prediction: 4% (89th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-330
Affected product: Windriver Vxworks
Published: 2015-08-04
Last modified: 2026-06-17

Description

Wind River VxWorks before 5.5.1, 6.5.x through 6.7.x before 6.7.1.1, 6.8.x before 6.8.3, 6.9.x before 6.9.4.4, and 7.x before 7 ipnet_coreip 1.2.2.0, as used on Schneider Electric SAGE RTU devices before J2 and other devices, does not properly generate TCP initial sequence number (ISN) values, which makes it easier for remote attackers to spoof TCP sessions by predicting an ISN value.

Frequently asked questions

What is CVE-2015-3963?: Wind River VxWorks before 5.5.1, 6.5.x through 6.7.x before 6.7.1.1, 6.8.x before 6.8.3, 6.9.x before 6.9.4.4, and 7.x before 7 ipnet_coreip 1.2.2.0, as used on Schneider Electric SAGE RTU devices before J2 and other devices, does not properly generate TCP initial sequence number (ISN) values, which makes it easier for remote attackers to spoof TCP sessions by predicting an ISN value.
How severe is CVE-2015-3963?: CVE-2015-3963 has a CVSS 2.0 base score of 5.8, rated medium severity.
Is CVE-2015-3963 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (89th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2015-3963?: CVE-2015-3963 primarily affects Windriver Vxworks. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2015-3963?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2015-3963 published?: CVE-2015-3963 was published on 2015-08-04 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:o:windriver:vxworks:*:*:*:*:*:*:*:*
cpe:2.3:o:windriver:vxworks:6.6.3:*:*:*:cert:*:*:*
cpe:2.3:o:windriver:vxworks:6.6.4:*:*:*:cert:*:*:*
cpe:2.3:o:windriver:vxworks:6.6.4.1:*:*:*:cert:*:*:*
cpe:2.3:o:windriver:vxworks:7.0:*:*:*:*:*:*:*

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