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CVE Record

CVE-2026-7598: libssh2 userauth.c userauth_password integer overflow

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.

CriticalCVSS 9.1Not KEV-listedUpdated
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Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

libssh2 1.11.0 and 1.11.1 contain an integer-overflow flaw in password authentication handling. A remote attack may affect integrity and availability, but the supplied evidence does not establish code execution or data theft. Organizations should urgently identify applications and appliances embedding affected libssh2 versions and apply the referenced patch or vendor-provided updates.

Executive priority

Treat as an urgent remediation item because the supplied CVSS score is 9.1 and indicates potential high integrity and availability impact without authentication. Prioritize confirmed affected, remotely reachable deployments. Maintain proportionate incident posture: the supplied evidence does not show active exploitation or inclusion in CISA KEV.

Technical view

CVE-2026-7598 affects userauth_password in src/userauth.c. Manipulation involving username_len or password_len can cause an integer overflow. CVSS 3.1 rates it 9.1: network-accessible, low complexity, unauthenticated, and requiring no user interaction, with high integrity and availability impact. The bundle identifies commit 256d04b60d80bf1190e96b0ad1e91b2174d744b1 as the patch.

Likely exposure

Exposure exists where libssh2 1.11.0 or 1.11.1 is directly installed, statically linked, bundled, or supplied through a vendor product and password authentication reaches the vulnerable function. The bundle does not identify specific downstream products or confirm whether every use is remotely reachable.

Exploitation context

The source bundle says the attack may be launched remotely, and the CVSS vector indicates no privileges or user interaction. However, CVE-2026-7598 is not listed as KEV, and the supplied sources provide no evidence of active exploitation, public weaponization, or a working exploit. Exact attacker control and triggering prerequisites remain insufficiently documented here.

Researcher notes

The reported weakness is an integer overflow involving username_len or password_len in userauth_password. The bundle does not establish the resulting corruption mechanism, practical input limits, affected architectures, or exploit reliability. Review the linked pull request and patch when assessing reachability and backports; do not infer code execution solely from the critical score.

Mitigation direction

  • Apply libssh2 commit 256d04b60d80bf1190e96b0ad1e91b2174d744b1 or an official vendor update containing it.
  • Prioritize internet-facing and security-sensitive systems using affected libssh2 password authentication.
  • Check downstream vendor advisories for bundled or backported libssh2 packages.
  • Restrict unnecessary network exposure while affected deployments await supported updates.

Validation and detection

  • Inventory direct, transitive, bundled, and statically linked libssh2 copies.
  • Confirm whether deployed versions are 1.11.0 or 1.11.1.
  • Determine whether applications invoke libssh2 password authentication on remotely reachable workflows.
  • Verify vendor package changelogs or source provenance include the referenced patch.
  • Run defensive regression tests covering unusually large authentication inputs after remediation.
Prepared
Confidence
medium
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-189: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-190: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2026-7598 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Critical
CVSS
9.1 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

5CVSS vectors
8Timeline events
2ADP providers
13Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: pocAutomatable: yesTechnical Impact: partial

CVSS vector scores

5 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
9.1CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H3.95.2redhat-SADP
7.5CVSS 2.0HighAV:N/AC:L/Au:N/C:P/I:P/A:P/E:ND/RL:OF/RC:C106.4VulDB
7.3CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:X/RL:O/RC:C3.93.4VulDB
7.3CVSS 3.0HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:X/RL:O/RC:C3.93.4VulDB
6.9CVSS 4.0MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X——VulDB

Vulnerability scoring details

Base CVSS 4.0 score

6.9Medium
CVSS 4.0 vector shape for CVE-2026-7598Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. Source timelineVulDB

    Advisory disclosed

  2. Source timelineVulDB

    VulDB entry created

  3. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  4. Source timelineVulDB

    VulDB entry last update

  5. ADP timelineredhat-SADP

    Made public.

  6. CVE publishedCVE Program

    The CVE record was published.

  7. ADP timelineredhat-SADP

    Reported to Red Hat.

  8. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPlibssh2: integer overflow via large username or password arguments
other:Red Hat severity ratingcvssV3_1
  • 2026-05-01T22:00:54.329Z: Reported to Red Hat.
  • 2026-05-01T21:30:11.006Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/alibssh21.11.0, 1.11.1Listed
Weakness

CWE details

CWE-189CWE-190

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-189 · source CWE mapping

Numeric Errors

Numeric Errors represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-190 · source CWE mapping

Integer Overflow or Wraparound

Integer Overflow or Wraparound represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs