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VulnerabilityPublished Updated

CVE-2026-20833: Microsoft Windows Server 2008 R2 Service Pack 1 · Weak Cryptography

Affects Microsoft Windows Server 2008 R2 Service Pack 1Source CVE Database V5

0

Not known to be exploited · CVSS 5.5 Medium : upgrade to 6.1.7601.28117 when convenient.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
5.5Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 44% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 6.1.7601.28117, 6.0.6003.23717, 6.2.9200.25868 +6
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 13 Jan 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
MicrosoftWindows Server 2008 R2 Service Pack 1Affected
  • >=6.1.7601.0 <6.1.7601.28117
Fixed in
  • 6.1.7601.28117
MicrosoftWindows Server 2008 R2 Service Pack 1 (Server Core installation)Affected
  • >=6.1.7601.0 <6.1.7601.28117
Fixed in
  • 6.1.7601.28117
MicrosoftWindows Server 2008 Service Pack 2Affected
  • >=6.0.6003.0 <6.0.6003.23717
Fixed in
  • 6.0.6003.23717
MicrosoftWindows Server 2008 Service Pack 2 (Server Core installation)Affected
  • >=6.0.6003.0 <6.0.6003.23717
Fixed in
  • 6.0.6003.23717
MicrosoftWindows Server 2012Affected
  • >=6.2.9200.0 <6.2.9200.25868
Fixed in
  • 6.2.9200.25868
MicrosoftWindows Server 2012 (Server Core installation)Affected
  • >=6.2.9200.0 <6.2.9200.25868
Fixed in
  • 6.2.9200.25868

AI-suggested

An official fix is available from Microsoft. Users should apply the security update referenced in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20833 to remediate this vulnerability.

Description

Use of a broken or risky cryptographic algorithm in Windows Kerberos allows an authorized attacker to disclose information locally.

References

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