Microsoft Exchange Server Information Disclosure

Microsoft Exchange Server Information Disclosure Vulnerability

CheckOps priority index

8.3/10 Patch within 24 h

Severity7.3

Probability9.8

Exploitation4/5

Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.

EPSS · today 98.2% higher than 99.9% of CVEs

CVSS 3.1 7.3 AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:

Exploited for 1,750 days 18 Jan 2022

CISA due date 01 Feb 2022 for US federal agencies

Exploitation probability EPSS · FIRST

EPSS probability (%)Percentile among all CVEs

Exploitation signals 4 / 5

KEV catalog (CISA)18 Jan 2022
Exploited in EUVD (ENISA)18 Jan 2022
Used by ransomwareno
EPSS above 10 %98.2%
No account, over the networkyes

What to do

Fix

Apply the vendor’s fix as soon as it is available.

CISA guidance: Apply updates per vendor instructions.

Meanwhile

Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.

Manufacturers (CRA)

Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained

Affected products

Microsoft Exchange Server 2019 Cumulative Update 8Microsoft Exchange Server 2016 Cumulative Update 20Microsoft Exchange Server 2019 Cumulative Update 9Microsoft Exchange Server 2016 Cumulative Update 19Microsoft Exchange Server 2013 Cumulative Update 23Exchange Server

Affected versions

15.02.0 <15.02.0792.013
15.01.0 <15.01.2242.008
15.02.0 <15.02.0858.010
15.01.0 <15.01.2176.012
15.00.0 <15.00.1497.015

Weaknesses (CWE)

CWE-287

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

14 Jul 2021
Published
18 Jan 2022
Exploitation reported (ENISA)
18 Jan 2022
Added to the KEV catalog
01 Feb 2022
CISA remediation due date
05 Oct 2026
EPSS peak: 98.2%

References

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