CVE Intelligence
High Memory corruption

CVE-2019-3855 — An integer overflow flaw which could lead to an out of bounds write was discovered in libssh2...

An integer overflow flaw which could lead to an out of bounds write was discovered in libssh2 before 1.8.1 in the way packets are read from the server. A remote attacker who compromises a SSH server may be able to execute code on the client system when a user connects to the server.

Published Mar 21, 2019 · Updated Oct 14, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: redhat

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 9.3% (30-day exploitation probability)+14
  • Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
9.29%
ahead of 95% of scored CVEs · Oct 14, 2026
Affects
Apple
Xcode and 13 more
CVSS base
8.8
High · 4 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Apple Xcode, Debian Debian Linux, Fedoraproject Fedora…).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. Apply the fixed version or the patch documented under Remediation.
  4. Exploitation requires user interaction: tighten email/web filtering and warn affected users.
  5. EPSS ahead of 95% of scored CVEs: prioritize it in the patch queue.
  6. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Apple Xcode < 11.0 Vulnerable NIST National Vulnerability Database
Debian Debian Linux version 8.0version 9.0 Vulnerable NIST National Vulnerability Database
Fedoraproject Fedora version 29version 30version 28 Vulnerable NIST National Vulnerability Database
Libssh2 Libssh2 < 1.8.1 Vulnerable NIST National Vulnerability Database
Netapp Ontap Select Deploy Administration Utility versions not specified by the source Vulnerable NIST National Vulnerability Database
Opensuse Leap version 42.3 Vulnerable NIST National Vulnerability Database
Oracle Peoplesoft Enterprise Peopletools version 8.56version 8.57 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux version 8.0 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux Desktop version 7.0 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux Server version 7.0 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux Server Aus version 7.6 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux Server Eus version 7.6 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux Server Tus version 7.6 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux Workstation version 7.0 Vulnerable NIST National Vulnerability Database
The libssh2 Project Libssh2 version 1.8.1 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
8.8 CVSS 3.1 High 2.8 5.9 nvd@nist.gov via NIST National Vulnerability Database
8.8 CVSS 3.1 High — — GitHub, Inc. via GitHub Security Advisories
7.5 CVSS 3.0 High 1.6 5.9 secalert@redhat.com via NIST National Vulnerability Database
7.5 CVSS 3.0 High — — redhat via CVE Program (cve.org) e CISA ADP
9.3 CVSS 2.0 High 8.6 10.0 nvd@nist.gov via NIST National Vulnerability Database
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)
Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 8.8 (NVD (NIST)) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-190 · Integer Overflow or Wraparound

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 9.29%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
web/proxy/WAF logsnetwork IDS/IPSendpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · the libssh2 project/libssh2
    Oct 14, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 14, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 14, 2026
  • Fix documented
    Oct 14, 2026 · NIST National Vulnerability Database
  • Affected products added · libssh2/libssh2, fedoraproject/fedora, debian/debian linux, netapp/ontap select deploy administration utility, redhat/en
    Oct 14, 2026 · NIST National Vulnerability Database
  • CVSS changed · 8.8
    Oct 14, 2026 · NIST National Vulnerability Database
  • Source status changed · → Modified
    Oct 14, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 14, 2026 · Alertas do Telegram
  • 2019
  • CVE published
    Mar 21, 2019 · redhat

Source activity

Repeated readings are counted rather than listed.

  • 2× References added · Oct 14, 2026 – Oct 14, 2026
  • 1× Official description updated · Oct 14, 2026 – Oct 14, 2026

References

34 on the record

Elsewhere on this site

Apple
every CVE for this vendor
Memory corruption
same class
CWE-190
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-104046 Sssd: sssd: denial of service via incomplete identity provider authentication requests 8d
  • CVE-2026-104045 Sssd: sssd: denial of service via race condition in autofs responder 8d
  • CVE-2026-104047 Sssd: sssd: information disclosure via query injection in entra id lookups 8d
  • CVE-2026-104048 Sssd: sssd: authorization bypass via cross-domain username collision in hbac evaluation 8d
  • CVE-2026-102558 Libsoup: libsoup: heap buffer overflow during websocket receive-buffer growth 16d
  • CVE-2026-102555 Libsoup: libsoup: heap buffer overflow via uninitialized length in data-uri base64 decoding 16d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2019-3855 is "An integer overflow flaw which could lead to an out of bounds write was discovered in libssh2...", rated High. It affects Xcode (Apple); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.8 describes technical severity. EPSS 9.29% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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