How severe is CVE-2026-43889?

CVE-2026-43889 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-43889 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (11th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-43889?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-43889 have an EU (EUVD) identifier?

Yes. CVE-2026-43889 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29333.

When was CVE-2026-43889 published?

CVE-2026-43889 was published on 2026-05-11 and last updated on 2026-06-17.

CVE-2026-43889

CVE-2026-43889 is a medium-severity vulnerability with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-863.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 0% (11th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-29333
Weakness: CWE-863
Published: 2026-05-11
Last modified: 2026-06-17

Description

Outline is a service that allows for collaborative documentation. Prior to 1.7.0, the shares.create API accepts both collectionId and documentId simultaneously and, when published=false, only verifies read access for each—skipping the "share" permission check. A subsequent shares.update authorizes publication using an OR policy (can share collection OR can share document), so an attacker who holds share permission on one unrelated collection can publish a share that exposes an arbitrary document they cannot legitimately share, making it publicly accessible to unauthenticated users. This vulnerability is fixed in 1.7.0.

Frequently asked questions

What is CVE-2026-43889?: Outline is a service that allows for collaborative documentation. Prior to 1.7.0, the shares.create API accepts both collectionId and documentId simultaneously and, when published=false, only verifies read access for each—skipping the "share" permission check. A subsequent shares.update authorizes publication using an OR policy (can share collection OR can share document), so an attacker who holds share permission on one unrelated collection can publish a share that exposes an arbitrary document they cannot legitimately share, making it publicly accessible to unauthenticated users. This vulnerability is fixed in 1.7.0.
How severe is CVE-2026-43889?: CVE-2026-43889 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-43889 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (11th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-43889?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-43889 have an EU (EUVD) identifier?: Yes. CVE-2026-43889 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29333.
When was CVE-2026-43889 published?: CVE-2026-43889 was published on 2026-05-11 and last updated on 2026-06-17.

References

https://github.com/outline/outline/security/advisories/GHSA-rg4j-pmch-w6pm

Other CWE-863 (Incorrect Authorization) vulnerabilities

CVE-2026-48286 — Critical (CVSS 10.0): Adobe Campaign Classic (ACC) versions 7.4.3 build 9396 and earlier are affected by an Incorrect Authorization…
CVE-2026-48303 — Critical (CVSS 10.0): Adobe Campaign Classic (ACC) versions 7.4.3 build 9394 and earlier are affected by an Incorrect Authorization…
CVE-2026-44330 — Critical (CVSS 10.0): free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's NEF mounts the…
CVE-2026-46595 — Critical (CVSS 10.0): Previously, CVE-2024-45337 fixed an authorization bypass for misused ssh server configurations; if any other type of…
CVE-2026-33105 — Critical (CVSS 10.0): Improper authorization in Microsoft Azure Kubernetes Service allows an unauthorized attacker to elevate privileges over…
CVE-2026-32213 — Critical (CVSS 10.0): Improper authorization in Azure AI Foundry allows an unauthorized attacker to elevate privileges over a network.

Browse all CWE-863 (Incorrect Authorization) vulnerabilities →