Threats / Microsoft / CVE-2023-41763
CVE-2023-41763
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Microsoft Skype for Business vulnerability
Microsoft Skype for Business contains a Server-Side Request Forgery vulnerability enabling privilege escalation. The flaw has been exploited in active attacks.
Verdict
Today item — known-exploited.
An authenticated attacker can exploit SSRF in Skype for Business to escalate privileges and access restricted resources. Active exploitation in the wild indicates immediate risk to deployed instances.
CISA KEV Yes · 2023-10-105EPSS 0.90353 (verify live)6CVSS 5.33CISA SSVC Exploitation: active · Automatable: yes · Impact: partial4Exploit Public PoC / detection · nuclei template11
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
2 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-10-10).
Probability (EPSS)
EPSS 0.90353 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:P/RL:O/RC:C) · Affected: Microsoft, Skype for Business. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.
Weakness (CWE)
Mapped to CWE-918 Server-Side Request Forgery (SSRF).CWE — CNA-assigned (CVE.org); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: yes · Technical Impact: partialCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog the same day the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
Public exploit available
Public exploit tooling is catalogued for this CVE (a public proof-of-concept / detection template). Catalog entries: nuclei template. We link the catalog page(s) only — no payload or code is hosted or restated here.Link, never host — the catalog page is the source; basicsecurity.net does not redistribute payloads.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I authenticate to Skype for Business and craft a malicious request that forces the server to make internal requests on my behalf.
Business
Attacker gains unauthorized access to internal network resources and sensitive data not directly exposed to external users.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I leverage the SSRF to interact with backend services and administrative interfaces running on the same network.
Business
Attacker escalates from standard user to administrative privileges, compromising system integrity and confidentiality.
3
Lateral reach — past segmentation narrative 3
Attacker
I use elevated privileges to modify user accounts, access call records, and exfiltrate communications data.
Business
Organization faces data breach, regulatory violations, and loss of customer trust in communications platform security.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05