How severe is CVE-2020-27653?

CVE-2020-27653 has a CVSS 3.x base score of 8.3, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-27653 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-27653?

CVE-2020-27653 primarily affects Synology Router Manager. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-27653?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2020-27653 published?

CVE-2020-27653 was published on 2020-10-29 and last updated on 2026-06-17.

CVE-2020-27653

CVE-2020-27653 is a high-severity vulnerability in Synology Router Manager with a CVSS 3.x base score of 8.3. 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-327.

Key facts

Severity: High (CVSS 3.x base score 8.3)
CVSS v2: 5.1
EPSS exploit prediction: 1% (53rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-327
Affected product: Synology Router Manager
Published: 2020-10-29
Last modified: 2026-06-17

Description

Algorithm downgrade vulnerability in QuickConnect in Synology Router Manager (SRM) before 1.2.4-8081 allows man-in-the-middle attackers to spoof servers and obtain sensitive information via unspecified vectors.

Frequently asked questions

What is CVE-2020-27653?: Algorithm downgrade vulnerability in QuickConnect in Synology Router Manager (SRM) before 1.2.4-8081 allows man-in-the-middle attackers to spoof servers and obtain sensitive information via unspecified vectors.
How severe is CVE-2020-27653?: CVE-2020-27653 has a CVSS 3.x base score of 8.3, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-27653 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-27653?: CVE-2020-27653 primarily affects Synology Router Manager. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-27653?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-27653 published?: CVE-2020-27653 was published on 2020-10-29 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:synology:router_manager:*:*:*:*:*:*:*:*
cpe:2.3:o:synology:diskstation_manager:6.2.3_25426:*:*:*:*:*:*:*

More vulnerabilities in Synology Router Manager

CVE-2023-32956 — Critical (CVSS 9.8): Improper neutralization of special elements used in an OS command ('OS Command Injection') vulnerability in CGI…
CVE-2020-27654 — Critical (CVSS 9.8): Improper access control vulnerability in lbd in Synology Router Manager (SRM) before 1.2.4-8081 allows remote attackers…
CVE-2018-1160 — Critical (CVSS 9.8): Netatalk before 3.1.12 is vulnerable to an out of bounds write in dsi_opensess.c. This is due to lack of bounds…
CVE-2017-14491 — Critical (CVSS 9.8): Heap-based buffer overflow in dnsmasq before 2.78 allows remote attackers to cause a denial of service (crash) or…
CVE-2019-11823 — High (CVSS 8.6): CRLF injection vulnerability in Network Center in Synology Router Manager (SRM) before 1.2.3-8017-2 allows remote…
CVE-2020-27649 — High (CVSS 8.3): Improper certificate validation vulnerability in OpenVPN client in Synology Router Manager (SRM) before 1.2.4-8081…

All CVEs affecting Synology Router Manager →

Other CWE-327 (Use of a Broken or Risky Cryptographic Algorithm) vulnerabilities

CVE-2026-50086 — Critical (CVSS 10.0): The Aqara IAM/SSO gateway (gw-builder.aqara.com) exposes bidirectional AES round-trups against the platform's signing…
CVE-2026-21718 — Critical (CVSS 10.0): An authentication bypass vulnerability exists in Copeland XWEB Pro version 1.12.1 and prior, enabling any attackers to…
CVE-2025-54426 — Critical (CVSS 9.9): Polkadot Frontier is an Ethereum and EVM compatibility layer for Polkadot and Substrate. In versions prior to commit…
CVE-2024-51478 — Critical (CVSS 9.9): YesWiki is a wiki system written in PHP. Prior to 4.4.5, the use of a weak cryptographic algorithm and a hard-coded…
CVE-2026-28252 — Critical (CVSS 9.8): A Use of a Broken or Risky Cryptographic Algorithm vulnerability in Trane Tracer SC, Tracer SC+, and Tracer Concierge…
CVE-2025-13476 — Critical (CVSS 9.8): Rakuten Viber Cloak mode in Android v25.7.2.0g and Windows v25.6.0.0–v25.8.1.0 uses a static and predictable TLS…

Browse all CWE-327 (Use of a Broken or Risky Cryptographic Algorithm) vulnerabilities →