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
Not known to be exploited · CVSS 5.5 Medium : upgrade to 6.1.7601.28117 when convenient.
Data as of 26 Oct 2026, 12:55 UTC
- 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:CExploitation evidence
Disclosed: evidence found.
CVE published 13 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| MicrosoftWindows Server 2008 R2 Service Pack 1 | Affected
| Fixed in
|
| MicrosoftWindows Server 2008 R2 Service Pack 1 (Server Core installation) | Affected
| Fixed in
|
| MicrosoftWindows Server 2008 Service Pack 2 | Affected
| Fixed in
|
| MicrosoftWindows Server 2008 Service Pack 2 (Server Core installation) | Affected
| Fixed in
|
| MicrosoftWindows Server 2012 | Affected
| Fixed in
|
| MicrosoftWindows Server 2012 (Server Core installation) | Affected
| Fixed in
|
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.