How severe is CVE-2026-56855?

CVE-2026-56855 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-56855 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (41st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-56855?

CVE-2026-56855 affects Golang Crypto. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-56855?

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-2026-56855 published?

CVE-2026-56855 was published on 2026-09-02 and last updated on 2026-09-04.

CVE-2026-56855

CVE-2026-56855 is a high-severity vulnerability in Golang Crypto with a CVSS 3.x base score of 7.5. 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-770.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (41st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-770
Affected product: Golang Crypto
Published: 2026-09-02
Last modified: 2026-09-04

Description

Previously, after a channel has been established, a malicious peer could send crafted messages that would deadlock the entire connection. Now, we handle all RFC 4254 channel messages; global requests are handled explicitly. Then, treat all other messages as a protocol error and tear the connection down instead of buffering and blocking.

Frequently asked questions

What is CVE-2026-56855?: Previously, after a channel has been established, a malicious peer could send crafted messages that would deadlock the entire connection. Now, we handle all RFC 4254 channel messages; global requests are handled explicitly. Then, treat all other messages as a protocol error and tear the connection down instead of buffering and blocking.
How severe is CVE-2026-56855?: CVE-2026-56855 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-56855 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (41st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-56855?: CVE-2026-56855 affects Golang Crypto. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-56855?: 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-2026-56855 published?: CVE-2026-56855 was published on 2026-09-02 and last updated on 2026-09-04.

References

Affected products (1)

cpe:2.3:a:golang:crypto:*:*:*:*:*:go:*:*

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