Is CVE-2026-55200 in the CISA KEV catalog?

No. CVE-2026-55200 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-55200?

CVE-2026-55200 has a CVSS v3 base score of 8.1 (Important).

What is the EPSS score for CVE-2026-55200?

CVE-2026-55200 has an EPSS score of 0.73% (50th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-55200?

Upgrade libssh2 on debian 13 to 1.11.1-1+deb13u1 or later. Fixes are available for 5 affected products.

CVE & CISA-KEV Catalog

CVE-2026-55200

HIGH

8.1

CVSS v3

NVD

Description

libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap memory and achieve remote code execution.

CWE-680

How to fix

Remediation Available

libssh2Debian

Fixed in:1.11.1-1+deb13u1CVE-2026-55200

Fixed in:1.11.1-4CVE-2026-55200

libssh2Rocky

Fixed in:main@srcRHSA-2026:29950

Fixed in:main@aarch64RHSA-2026:29950

Fixed in:main@noarchRHSA-2026:29950

Fixed in:main@x86_64RHSA-2026:29950

libssh2Red Hat / RHEL

Fixed in:main@noarchRHSA-2026:29950

Fixed in:main@aarch64RHSA-2026:29950

Fixed in:main@x86_64RHSA-2026:29950

Fixed in:main@srcRHSA-2026:29950

libssh2Ubuntu

Fixed in:1.11.0-4.1ubuntu0.24.04.2USN-8486-1

Fixed in:1.11.1-1ubuntu0.25.10.2USN-8486-1

libssh2-1t64Ubuntu

Fixed in:1.11.0-4.1ubuntu0.24.04.2USN-8486-1

Fixed in:1.11.1-1ubuntu0.25.10.2USN-8486-1

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploit Intelligence

0.73%probability of exploitation in 30 days

50thpercentile

Moderate risk: more likely to be exploited than 50% of all known CVEs.

References

Patch2

Exploit1

web.archive.org

Third-Party Advisory1

vulncheck.com

Related Vulnerabilities

Other CWE-680 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2022-24834	High	7.0	41%	-	Fix
CVE-2021-32761	High	7.5	31%	-	Fix
CVE-2020-6116	High	7.8	28%	-	-
CVE-2021-40417	Critical	9.8	16%	-	-
CVE-2021-32628	High	7.5	13%	-	Fix
CVE-2018-8787	Critical	9.8	8.4%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-14.