CVE-2026-55200

Exploitation

Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.

SSVC decision

• ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
• AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
• Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

3.87% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 90.1% of scored records. A rank, not a probability.

NVD base score

9.2 (CVSS v4.0), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

NVD analysis status

Modified. NVD last modified this record on 2026-10-22.

Red Hat severity

Moderate. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2026-06-17 19:03Z4 MO AGO

Last updated

2026-10-22 18:33Z7 DAYS AGO

Reserved

2026-06-16

Assigning CNA

VulnCheck

Record state

PUBLISHED

Severity

Critical (CVSS 9.2)

CNA CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Weaknesses

• CWE-680Integer Overflow to Buffer OverflowCompound
• CWE-787Out-of-bounds WriteBase

Data version

5.2

Document digest

eb6de9cc8f3f73f0f791c69bf7b76f66f9727831aa0fcd8add9e2b622bf97721

• github.comPull Requesthttps://github.com/libssh2/libssh2/pull/2052issue-tracking
• github.comPatch Commithttps://github.com/libssh2/libssh2/commit/97acf3dfda80c91c3a8c9f2372546301d4a1a7a8patch
• www.vulncheck.comhttps://www.vulncheck.com/advisories/libssh2-out-of-bounds-write-via-unchecked-packet-length-in-transport-cthird-party-advisory
• web.archive.orghttps://web.archive.org/web/20260623211210/https://github.com/bikini/exploitarium/tree/main/libssh2-cve-2026-55200-pocexploit