How severe is CVE-2007-4991?

CVE-2007-4991 has a CVSS 2.0 base score of 5.0, rated medium severity.

Is CVE-2007-4991 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 16% (97th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2007-4991?

CVE-2007-4991 primarily affects Microsoft Isa Server. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2007-4991?

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

When was CVE-2007-4991 published?

CVE-2007-4991 was published on 2007-09-21 and last updated on 2026-06-16.

CVE-2007-4991

CVE-2007-4991 is a medium-severity vulnerability in Microsoft Isa Server with a CVSS 2.0 base score of 5.0. Its EPSS exploit-prediction score of 16% places it in the 97th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-200.

Key facts

Severity: Medium (CVSS 2.0 base score 5.0)
EPSS exploit prediction: 16% (97th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-200
Affected product: Microsoft Isa Server
Published: 2007-09-21
Last modified: 2026-06-16

Description

The SOCKS4 Proxy in Microsoft Internet Security and Acceleration (ISA) Server 2004 SP1 and SP2 allows remote attackers to obtain potentially sensitive information (the destination IP address of another user's session) via an empty packet.

Frequently asked questions

What is CVE-2007-4991?: The SOCKS4 Proxy in Microsoft Internet Security and Acceleration (ISA) Server 2004 SP1 and SP2 allows remote attackers to obtain potentially sensitive information (the destination IP address of another user's session) via an empty packet.
How severe is CVE-2007-4991?: CVE-2007-4991 has a CVSS 2.0 base score of 5.0, rated medium severity.
Is CVE-2007-4991 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 16% (97th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2007-4991?: CVE-2007-4991 primarily affects Microsoft Isa Server. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2007-4991?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2007-4991 published?: CVE-2007-4991 was published on 2007-09-21 and last updated on 2026-06-16.

References

Affected products (2)

cpe:2.3:a:microsoft:isa_server:2004:sp1:*:*:*:*:*:*
cpe:2.3:a:microsoft:isa_server:2004:sp2:*:*:*:*:*:*

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