How severe is CVE-2020-27658?

CVE-2020-27658 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability low.

Is CVE-2020-27658 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-27658?

CVE-2020-27658 affects Synology Router Manager. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-27658?

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-2020-27658 published?

CVE-2020-27658 was published on 2020-10-29 and last updated on 2026-06-17.

CVE-2020-27658

CVE-2020-27658 is a high-severity vulnerability in Synology Router Manager with a CVSS 3.x base score of 7.1. 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-732.

Key facts

Severity: High (CVSS 3.x base score 7.1)
CVSS v2: 4.3
EPSS exploit prediction: 1% (67th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-732
Affected product: Synology Router Manager
Published: 2020-10-29
Last modified: 2026-06-17

Description

Synology Router Manager (SRM) before 1.2.4-8081 does not include the HTTPOnly flag in a Set-Cookie header for the session cookie, which makes it easier for remote attackers to obtain potentially sensitive information via script access to this cookie.

Frequently asked questions

What is CVE-2020-27658?: Synology Router Manager (SRM) before 1.2.4-8081 does not include the HTTPOnly flag in a Set-Cookie header for the session cookie, which makes it easier for remote attackers to obtain potentially sensitive information via script access to this cookie.
How severe is CVE-2020-27658?: CVE-2020-27658 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability low.
Is CVE-2020-27658 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-27658?: CVE-2020-27658 affects Synology Router Manager. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-27658?: 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-2020-27658 published?: CVE-2020-27658 was published on 2020-10-29 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:synology:router_manager:*:*:*:*:*:*:*:*

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