NVD / CVE Program· CNA microsoft

CVE-2020-17144: Microsoft Exchange Remote Code Execution Vulnerability

HighCVSS 8.4 · v3.1KEVWeaponized No fix recorded

Noroxi assessment

Priority: This week (action score 74/100)

CISA has confirmed exploitation in the wild (Nov 3, 2021). Remediation deadline for US federal agencies: May 3, 2022.
Probability of exploitation in the next 30 days: 36.5% (FIRST EPSS); higher than 98.5% of all records.
Anyone who can reach it over the internet can trigger it. Administrator privileges are required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
According to CISA the attack is automatable: targets can be found by mass scanning.
According to the record, no fixed version is available yet.
Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Don’t wait for the next maintenance window. Until a fix is released, restrict access to the affected component and follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · CISA KEV · FIRST EPSS

BDU:2020-05864

Published: Dec 9, 2020
Updated: Jun 16, 2026
EPSS: 36.5% · 98th percentile
CWE: CWE-502

Report tools

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Action score

This week

Don’t wait for the next maintenance window.

CVSS: 33 / 40 · 8.4 / 10
CISA KEV: 30 / 30 · Listed
EPSS: 11 / 30 · 36.5%

CISA SSVC decision

Exploitation: active
Automatable: yes
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · microsoft: 8.4; NVD has not scored this yet; the score shown is the CNA’s.

CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:H/E:P/RL:O/RC:C

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Actively exploited in the wild

CISA added this to its Known Exploited Vulnerabilities catalog on Nov 3, 2021. That signals real attacks, not theory.

Remediation deadline for US federal agencies: May 3, 2022.

Get told when this record changes

In CISA KEV: exploitation in the wild confirmed
Weaponized exploit exists
No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
microsoft	exchange server	cpe:2.3:a:microsoft:exchange_server

Using exchange server? Add it to your stack and be the first to know about CVEs like this one. (Email server)

Versions reported by the vendor

Affected version ranges reported by the assigning authority (microsoft). Independent of NVD's CPE analysis and usually ahead of it.

Microsoft Microsoft Exchange Server 2010 Service Pack 3 Update Rollup 31
- before publicationaffected

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

microsoft exchange server2010

Same product

microsoft: all records

Other highest-scoring records for the same primary product.

CVE-2021-34523Microsoft Exchange Server Elevation of Privilege VulnerabilityKEV
96Now
CVE-2021-34473Microsoft Exchange Server Remote Code Execution VulnerabilityKEV
96Now
CVE-2021-26855Microsoft Exchange Server Remote Code Execution VulnerabilityKEV
96Now

Published before and after this one in the same product

← EarlierCVE-2020-17142Dec 9, 2020 · Microsoft Exchange Remote Code Execution Vulnerability
37Monitor
← EarlierCVE-2020-17143Dec 9, 2020 · Microsoft Exchange Server Information Disclosure Vulnerability
56Plan
Later →CVE-2021-1730Feb 25, 2021 · Microsoft Exchange Server Spoofing Vulnerability
22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

Weaponized

A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.

Evidence

Proof-of-concept repository on GitHub ×2

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
Source	Kind	Date
Proof-of-concept repository on GitHub	stars:157	2020-12-09
Proof-of-concept repository on GitHub	stars:158	2020-12-09

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

First PoCDec 9, 2020-1 d
PublishedDec 9, 2020
CISA KEVNov 3, 2021+328 d
TodayNov 13, 2026+2164 d

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

TR-20-1026 · Dec 9, 2020(Microsoft Aralık 2020 Güvenlik Güncellemelerini Yayınladı)

All national notices →

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
Administrator privileges are required.
A user must open a link or visit a page.
No special conditions are required; it is repeatable.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Impact can extend beyond the vulnerable component (scope changes).

Attack vector: Network
Attack complexity: Low
Privileges required: High
User interaction: Required
Scope: Changed
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-502 · Deserialization of Untrusted Data

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:H

nvd-secondary

Root cause

Data received over the network is deserialized into the language’s native object format without verifying its source. Code paths inside the object can be triggered during deserialization.

The bug in code

The whole CWE-502 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

python

1payload = sock.recv(65536)
2job = pickle.loads(payload)

Fixed

python

1payload = sock.recv(65536)
2if not hmac.compare_digest(sign(payload), header_sig):
3    raise PermissionError("invalid signature")
4job = JobSchema.validate(json.loads(payload))

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

Object InjectionCAPEC-586likelihood: Medium · High

ATT&CK techniques

—

Change log (0)

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

msrc.microsoft.com/update-guide/vulnerability/CVE-2020-17144

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records