Threats / Microsoft / CVE-2023-29357
CVE-2023-29357
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Microsoft SharePoint Server vulnerability
Microsoft SharePoint Server vulnerability allows unauthenticated attackers with spoofed JWT tokens to bypass authentication and gain administrator privileges, enabling network attacks.
Verdict
Today item, not a backlog item.
An authentication bypass flaw in SharePoint Server permits attackers holding forged JWT credentials to escalate to administrative access without legitimate credentials, facilitating unauthorized system compromise and data exfiltration.
CISA KEV Yes · 2024-01-105Ransomware use Flagged5EPSS 0.99649 (verify live)6Exploit Weaponized · public PoC7CVSS 9.83CISA SSVC Exploitation: active · Automatable: yes · Impact: total4
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Fully weaponized — public exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
533 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 2024-01-10), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.99649 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C) · Affected: Microsoft, SharePoint Server. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.
Weakness (CWE)
Mapped to CWE-303 CWE-303 — weakness family: Authentication.CWE — CNA-assigned (CVE.org); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: yes · Technical Impact: totalCISA'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 211 days after 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 functional/weaponized public exploit). Catalog entries: Metasploit module, 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 obtain or forge JWT authentication tokens through credential theft or cryptographic weakness.
Business
Attackers gain entry to SharePoint infrastructure without legitimate user credentials, circumventing perimeter security controls.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I present the spoofed JWT tokens to SharePoint Server to bypass authentication mechanisms.
Business
Authentication systems fail to validate token legitimacy, allowing unauthorized access to proceed unchallenged.
3
Lateral reach — past segmentation narrative 3
Attacker
I escalate my access level to administrator privileges within the compromised SharePoint instance.
Business
Attackers gain full administrative control over document repositories, user accounts, and system configurations.
4
Data at risk — exfiltration narrative 4
Attacker
I exfiltrate sensitive documents, deploy malware, or establish persistence mechanisms across the SharePoint environment.
Business
Confidential business data is stolen, systems are compromised for ransomware deployment, and organizational operations are disrupted.
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