CVE-2026-45076
CVE-2026-45076 is a low-severity vulnerability in Element Synapse with a CVSS 3.x base score of 2.7. 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-20.
Key facts
- Severity: Low (CVSS 3.x base score 2.7)
- CVSS v4: 5.1
- EPSS exploit prediction: 0% (30th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-32934
- Weakness: CWE-20
- Affected product: Element Synapse
- Published:
- Last modified:
Description
Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, in federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients. Clients could therefore fail to display room history. This vulnerability is fixed in 1.152.1.
Frequently asked questions
- What is CVE-2026-45076?
- Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, in federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients. Clients could therefore fail to display room history. This vulnerability is fixed in 1.152.1.
- How severe is CVE-2026-45076?
- CVE-2026-45076 has a CVSS 3.x base score of 2.7, rated low severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
- Is CVE-2026-45076 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-45076?
- CVE-2026-45076 affects Element Synapse. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-45076?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2026-45076 have an EU (EUVD) identifier?
- Yes. CVE-2026-45076 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-32934.
- When was CVE-2026-45076 published?
- CVE-2026-45076 was published on 2026-05-28 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:a:element:synapse:*:*:*:*:*:*:*:*
More vulnerabilities in Element Synapse
- CVE-2026-45078 — Medium (CVSS 5.5): Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, local authenticated users can cause…
All CVEs affecting Element Synapse →
Other CWE-20 (Improper Input Validation) vulnerabilities
- CVE-2026-93952 — Critical (CVSS 10.0): VeloCloud Orchestrator (VCO) on-prem has a security issue where this issue may allow a remote attacker to access…
- CVE-2026-77554 — Critical (CVSS 10.0): A malicious actor with access to the network could exploit an Improper Input Validation vulnerability found in UniFi…
- CVE-2026-77537 — Critical (CVSS 10.0): A malicious actor with access to the network could exploit an Improper Input Validation vulnerability found in UniFi…
- CVE-2026-48056 — Critical (CVSS 10.0): Streambert is a cross-platform Electron Desktop App to stream and download video content. Versions prior to 2.5.0…
- CVE-2026-33267 — Critical (CVSS 10.0): Improper Input Validation vulnerability in Apache Traffic Server. This issue affects Apache Traffic Server: from 9.2.0…
- CVE-2026-47668 — Critical (CVSS 10.0): DbGate is cross-platform database manager. In versions 7.1.8 and prior, DbGate's JSON script runner (`POST…
Browse all CWE-20 (Improper Input Validation) vulnerabilities →