HighCVE-2026-7598

libssh2 userauth.c userauth_password integer overflow (CVE-2026-7598)

Published 01.05.2026Last modified 01.09.2026Sources: Debian, SUSE, Debian LTS, BSI, Msrc Update Guide, Red Hat, CVE.org, EUVD, Ubuntu

What is affected, what to do

A security vulnerability has been detected in libssh2 up to 1.11.1. The impacted element is the function userauth_password of the file src/userauth.c.

The available sources name no fixed version. Check the vendor guidance in the references below.

Affected: Libssh2 eq 1.11.0..1.11.0
Libssh2 eq 1.11.1..1.11.1

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Metrics

7.3

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: NVD, CVSS v3

7.3

CVSS v3

Severity High on the scale from 0 to 10.

Source: Debian, SUSE, Debian LTS, BSI, Msrc Update Guide, Red Hat, CVE.org, EUVD, Ubuntu

0.5 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 40.3

Show all metrics

Severity: High
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 66.35 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: no public PoC known
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 7.3 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 7.3
CVSS v4 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 6.9
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 0.5 %; Low — model estimates < 1% exploitation likelihood.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 40.3; High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: —
Published: 01.05.2026
CISA assessment (SSVC): Exploitation: proof of concept · automatable · Technical impact: partial; Source: CISA Vulnrichment, as of 4 May 2026
CWE CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect. Read in glossary: CWE-190, CWE-189

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

A security vulnerability has been detected in libssh2 up to 1.11.1. The impacted element is the function userauth_password of the file src/userauth.c. Such manipulation of the argument username_len/password_len leads to integer overflow. The attack may be launched remotely. The name of the patch is 256d04b60d80bf1190e96b0ad1e91b2174d744b1. A patch should be applied to remediate this issue.

Source: Debian Security Advisories, suse_csaf, Debian LTS Advisories, BSI WID Portal, BSI CSAF, Microsoft Security Update Guide, redhat_csaf, cvelistv5, NVD (NIST), ENISA EUVD, Ubuntu Security Notices, CVE.org (MITRE)

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
—	libssh2	`1.11.0` `1.11.1`	— —
libssh2	libssh2	`≤ 1.11.1`	—
Microsoft	Azure Linux	`azl3`	—
Oracle	PeopleSoft	`9.2` `9.1` `8.61-8.63`	— — —

Vendors and products

Affected operating systems

Affected operating systems

Linux	debian	libssh2	`bookworm`
Linux	debian	libssh2	`trixie`

Weakness classes (CWE)

CWE-190Integer Overflow or Wraparound
Base
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
Entry at MITRE CWE-190
CWE-189Numeric Errors
Category
Entry at MITRE CWE-189

References & sources

vuldb.comVDB-360555 | libssh2 userauth.c userauth_password integer overfloweuvd, Vulnerability database, Technical description
vuldb.comVDB-360555 | CTI Indicators (IOB, IOC, IOA)euvd, signature, Permissions required
vuldb.comSubmit #805564 | libssh2 <= 1.11.1 Integer Overfloweuvd, Third-party advisory
github.comlibssh2/libssh2/pull/1858euvd, Issue tracking, Patch
github.comlibssh2/libssh2/commit/256d04b60d80bf1190e96b0ad1e91b2174d744b1euvd, Patch
github.comlibssh2/libssh2euvd, Product
access.redhat.comsecurity/cve/CVE-2026-7598Vulnerability database, x_refsource_REDHAT
bugzilla.redhat.comRHBZ#2464597Issue tracking, x_refsource_REDHAT
security.access.redhat.comdata/csaf/v2/vex/2026/cve-2026-7598.jsonx_sadp-csaf-vex
access.redhat.comerrata/RHSA-2026:61752Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:7021Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:16736Vendor advisory, x_refsource_REDHAT

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

01.09.2026Record modifiedRed Hat ADP

New references:

and 2 more references

Show 11 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:16736
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:61752
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:7021
Reference	added	—	https://access.redhat.com/security/cve/CVE-2026-7598
Reference	added	—	https://bugzilla.redhat.com/show_bug.cgi?id=2464597
Reference	added	—	https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-7598.json
Reference	removed	https://access.redhat.com/errata/RHSA-2026:16736	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:7021	—
Reference	removed	https://access.redhat.com/security/cve/CVE-2026-7598	—
Reference	removed	https://bugzilla.redhat.com/show_bug.cgi?id=2464597	—
Reference	removed	https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-7598.json	—

Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

01.09.2026Record modifiedVulDB

New references:

and 2 more references

Show 18 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://github.com/libssh2/libssh2/
Reference	added	—	https://github.com/libssh2/libssh2/commit/256d04b60d80bf1190e96b0ad1e91b2174d744b1
Reference	added	—	https://github.com/libssh2/libssh2/pull/1858
Reference	added	—	https://vuldb.com/submit/805564
Reference	added	—	https://vuldb.com/vuln/360555
Reference	added	—	https://vuldb.com/vuln/360555/cti
Reference	removed	https://github.com/libssh2/libssh2/	—
Reference	removed	https://github.com/libssh2/libssh2/commit/256d04b60d80bf1190e96b0ad1e91b2174d744b1	—
Reference	removed	https://github.com/libssh2/libssh2/pull/1858	—
Reference	removed	https://vuldb.com/submit/805564	—
Reference	removed	https://vuldb.com/vuln/360555	—
Reference	removed	https://vuldb.com/vuln/360555/cti	—
Reference type	removed	https://github.com/libssh2/libssh2/ Types: Product	—
Reference type	removed	https://github.com/libssh2/libssh2/commit/256d04b60d80bf1190e96b0ad1e91b2174d744b1 Types: Patch	—
Reference type	removed	https://github.com/libssh2/libssh2/pull/1858 Types: Issue Tracking	—
Reference type	removed	https://vuldb.com/submit/805564 Types: Third Party Advisory, VDB Entry	—
Reference type	removed	https://vuldb.com/vuln/360555 Types: Third Party Advisory, VDB Entry	—
Reference type	removed	https://vuldb.com/vuln/360555/cti Types: Permissions Required, VDB Entry	—

Source identifier: cna@vuldb.com

01.09.2026Record modifiedCISA ADP

New references:

https://vuldb.com/submit/805564

Show 3 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://vuldb.com/submit/805564
Reference	removed	https://vuldb.com/submit/805564	—
Reference type	removed	https://vuldb.com/submit/805564 Types: Third Party Advisory, VDB Entry	—

Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

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