CVE-2017-8621: Microsoft Corporation Microsoft Exchange Server 2010 SP3, Exchange Server 2013 SP3, Exchange Server 2013 CU16, and Exchange Server 2016 CU5.: URL Redirection to Untrusted Site ('Open Redirect')

Recommended actionScheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available

What, why and how

Microsoft Exchange Server 2010 SP3, Exchange Server 2013 SP3, Exchange Server 2013 CU16, and Exchange Server 2016 CU5 allows an open redirect vulnerability that could lead to spoofing, aka "Microsoft Exchange Open Redirect Vulnerability".

What

Why

The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Why

The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.

How

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation

Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.

No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material

Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.

None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path: a network path → URL Redirection to Untrusted Site ('Open Redirect') → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface: Network
Privileges required: None: unauthenticated exploitation is possible
User interaction: Required interaction required
Attack complexity: Low: no specialised conditions are recorded
Security boundary: Changed: exploitation can affect a different security authority
Weakness ? CWE means Common Weakness Enumeration: a standard category for the underlying weakness.: CWE-601 ↗
CWE-601: URL Redirection to Untrusted Site ('Open Redirect'). The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.
CVSS vector ? CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Common Vulnerability Scoring System 3.0: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SChangedScope: The attack can affect a component governed by a different security authority.CLowConfidentiality impact: A successful attack can cause a limited loss.ILowIntegrity impact: A successful attack can cause a limited loss.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land: No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.

NetworkUnauthenticatedCWE-601

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2017-17570Official EUVD mapping

0 linked advisory records.

Official EUVD record ↗

Canadian Centre for Cyber Security · English · AV17-100Microsoft security updates

557, CVE-2017-8559, CVE-2017-8560, CVE-2017-8561, CVE-2017-8562, CVE-2017-8563, CVE-2017-8564, CVE-2017-8565, CVE-2017-8566, CVE-2017-8569, CVE-2017-8570, CVE-2017-8573, CVE-2017-8574, CVE-2017-8577, CVE-2017-8578, CVE-2017-8580, CVE-2017-8581, CVE-2017-8582, CVE-2017-8584, CVE-2017-8585, CVE-2017-8587, CVE-2017-8588, CVE-2017-8589, CVE-2017-8590, CVE-2017-8592, CVE-2017-8594, CVE-2017-8595, CVE-2017-8596, CVE-2017-8598, CVE-2017-8599, CVE-2017-8601, CVE-2017-8602, CVE-2017-8603, CVE-2017-8604, CVE-2017-8605, CVE-2017-8606, CVE-2017-8607, CVE-2017-8608, CVE-2017-8609, CVE-2017-8610, CVE-2017-8611, CVE-2017-8617, CVE-2017-8618, CVE-2017-8619, CVE-2017-8621 Suggested Action CCIRC recommends that system administrators test and deploy the vendor-released updates to affected applications accordingly. References: https://portal.msrc.microsoft.com/en-us/security-guidance/releasenotedetail/f2b16606-4945-e711-80dc-000d3a32fc99

Official advisory ↗

CERT-FR · French · CERTFR-2017-AVI-210Multiples vulnérabilités dans les produits Microsoft

De multiples vulnérabilités ont été corrigées dans les produits Microsoft . Elles permettent à un attaquant de provoquer un déni de service, un contournement de la politique de sécurité et une élévation de privilèges.

Official advisory ↗

JVN iPedia · Japanese · JVNDB-2017-005132Microsoft Exchange Server におけるオープンリダイレクトの脆弱性

Microsoft Exchange Server には、オープンリダイレクトの脆弱性が存在します。ベンダは、本脆弱性を「Microsoft Exchange のオープンリダイレクトの脆弱性」として公開しています。

Official advisory ↗

KISA KrCERT/CC · Korean · KNVD-4773MS 7월 보안 위협에 따른 정기 및 기타 보안 업데이트 권고

025342, 4025344 ##### □ 해결책 o 영향 받는 소프트웨어를 이용하는 경우 마이크로소프트사의 보안 패치 적용 Office 보안 업데이트 ##### □ 설명 o 이용자가 특수 제작된 악성 Office 파일을 열람하는 경우, 원격코드실행이 허용되는 취약점 o 관련취약점 : - 권한상승 취약점(CVE-2017-8569) - 원격코드실행 취약점(CVE-2017-0243, 8501, 8502, 8570) o 영향 : 원격코드실행 o 중요도 : 중요 o 관련 KB 번호 - 2880514, 3191833, 3191894, 3191897, 3191902, 3191907, 3203459, 3203468, 3203469, 3203477, 3212224, 3213537, 3213544, 3213545, 3213555, 3213559, 3213624, 3213640, 3213657 ##### □ 해결책 o 영향 받는 소프트웨어를 이용하는 경우 마이크로소프트사의 보안 패치 적용 Exchange Server 보안 업데이트 ##### □ 설명 o 이용자가 특수하게 제작된 악성 URL 링크를 클릭할 경우, 악성 사이트로 redirect되어 권한상승이 발생하는 취약점 o 관련취약점 : - 권한상승 취약점(CVE-2017-8559, 8560) - 스푸핑 취약점(CVE-2017-8621) o 영향 : 권한상승 o 중요도 : 중요 o 관련 KB 번호 - 4018588 ##### □ 해결책 o 영향 받는 소프트웨어를 이용하는 경우 마이크로소프트사의 보안 패치 적용 .NET Framework 보안 업데이트 ##### □ 설명 o 공격자에 의해 .NET Framework 구성요소에서 비정상적인 유효성 검사가 이루어질 경우, 서비스거부가 발생하는 취약점 o 관련취약점 : - 서비스거부 취약점(CVE-2017-8585) o 영향 : 서비스거부 o 중요도 : 중요 o 관련 KB 번호 - 4025338, 4025339, 4025342, 4025344 ##### □ 해결책 o 영향 받는 소프트웨어를 이용하는 경우 마이크로소프트사의 보안 패치 적용 Adobe Flash Player 보안 업데이트 ##### □ 설명 o 지원되는 모든 버전의 Windows 8.1, Windows Server 2012, Windows Server 2012 R2, Windows RT 8.1, Windows 10 및 Windows Server 2016에 설치된 Adobe Flash Player의 취약점을 해결 o 관련취약점 : - Adobe 보안 업데이트 APSB17-21에 설명된 취약점 o 영향 : 원격코드실행 o 중요도 : 긴급 o 관련 KB번호 - 4025376

Official advisory ↗

Patch and workaround

Operational remediation based on structured source evidence.

Status ? Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.: Patch available
Affected: Microsoft Exchange Server 2010 SP3, Exchange Server 2013 SP3, Exchange Server 2013 CU16, and Exchange Server 2016 CU5.: Microsoft Exchange
Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action: Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround: No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.

Evidence and provenance

Published 11 Jul 2017 · Last source change 16 Sept 2024, 23:45 UTC · CWE-601 · URL Redirection to Untrusted Site ('Open Redirect')

CVE recordCVE.org · 5.1

CVSS sourceNIST NVD

EPSS source

The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.

FIRST · tracked since 2026-09-01

European sourceENISA EUVD · EUVD-2017-17570

Product sourceCNA

Remediation sourceCVE/CNA references

CWE sourceNIST NVD

NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗

1 Sep 2026, 02:42 UTC
ENISA EUVD mappingEUVD-2017-17570 was added to the official ENISA EUVD mapping for this CVE.
Before
not recorded
After
{"euvdId":"EUVD-2017-17570"}
ENISA EUVD ↗
16 Sep 2024, 23:45 UTC
Vendor guidanceAuthoritative vendor guidance changed: added patch: portal.msrc.microsoft.com/CVE-2017-8621; added remediation: portal.msrc.microsoft.com/CVE-2017-8621.
Before
no authoritative guidance recorded
After
patch: portal.msrc.microsoft.com/CVE-2017-8621 · remediation: portal.msrc.microsoft.com/CVE-2017-8621
portal.msrc.microsoft.com ↗
16 Sep 2024, 23:45 UTC
Affected versionsThe structured affected or fixed version information changed.
Before
Microsoft Exchange · Fixed: No fixed version is explicitly recorded in the structured CVE data.
After
Microsoft Exchange · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
CNA ↗
16 Sep 2024, 23:45 UTC
Remediation statusRemediation status changed from Awaiting fix to Patch available.
Before
Awaiting fix
After
Patch available
portal.msrc.microsoft.com ↗
16 Sep 2024, 23:45 UTC
SeveritySeverity changed from Unknown to Medium.
Before
Unknown
After
Medium
NIST NVD ↗
16 Sep 2024, 23:45 UTC
CVSS scoreCVSS score changed from not recorded to 6.1 (CVSS 3.0 · NIST NVD · CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N).
Before
not recorded
After
6.1 (CVSS 3.0 · NIST NVD · CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N)
NIST NVD ↗
16 Sep 2024, 23:45 UTC
Catalogue recordCVE added to the BlackTree catalogue.
CNA ↗

2017-07-11CVE published

2024-09-16Fixed release or patch reference recorded

ENISA EUVD · EUVD-2017-17570↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗

Technical terms and abbreviations used in this report

CVE: Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS: Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS: Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE: Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA: CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP: Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD: National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT: A computer security incident response team that publishes warnings or coordinates incident response.
PoC: Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF: Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL: Living off the land: abuse of legitimate tools or system functions during an attack.

Microsoft Corporation Microsoft Exchange Server 2010 SP3, Exchange Server 2013 SP3, Exchange Server 2013 CU16, and Exchange Server 2016 CU5.: URL Redirection to Untrusted Site ('Open Redirect')

Published severity in operational context

Evidence used

Compensating controls

Verification

National CERT insights
?
CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

ENISA European Vulnerability Database

EUVD-2017-17570

What, why and how

Exploit reality and attack path

Official authority intelligence

Patch and workaround

Evidence and provenance

What changed after publication