HighCVE-2016-0778

    OpenBSD OpenSSH: Heap-Based Buffer Overflow (CVE-2016-0778)

    Published Sources: CVE.org

    What is affected, what to do

    The (1) roaming_read and (2) roaming_write functions in roaming_common.c in the client in OpenSSH 5.x, 6.x, and 7.x before 7.1p2, when certain proxy and forward options are enabled, do not properly maintain connection file descriptors, which allows remote servers to cause a denial of service (heap-based buffer overflow) or possibly have unspecified other impact by requesting many forwardings.

    An exploit is publicly available. The available sources name no fixed version. Check the vendor guidance in the references below.

    Affected
    • Oracle Linux eq 7..7
    • Oracle Solaris eq 11.3..11.3
    • OpenBSD OpenSSH eq 5.4..5.4
    • OpenBSD OpenSSH eq 5.5..5.5
    • OpenBSD OpenSSH eq 5.6..5.6
    • OpenBSD OpenSSH eq 5.7..5.7
    • OpenBSD OpenSSH eq 5.8..5.8
    • OpenBSD OpenSSH eq 5.9..5.9
    • OpenBSD OpenSSH eq 6.0..6.0
    • OpenBSD OpenSSH eq 6.1..6.1
    • OpenBSD OpenSSH eq 6.2..6.2
    • OpenBSD OpenSSH eq 6.3..6.3
    • OpenBSD OpenSSH eq 6.4..6.4
    • OpenBSD OpenSSH eq 6.5..6.5
    • OpenBSD OpenSSH eq 6.6..6.6
    • OpenBSD OpenSSH eq 6.7..6.7
    • OpenBSD OpenSSH eq 6.8..6.8
    • OpenBSD OpenSSH eq 6.9..6.9
    • OpenBSD OpenSSH eq 7.0..7.0
    • OpenBSD OpenSSH eq 7.1..7.1
    • Apple Mac OS X lte 10.9.0..10.9.5
    • Apple Mac OS X lte 10.10.0..10.10.5
    • Apple Mac OS X lte 10.11.0..10.11.3
    • Hp Virtual Customer Access System (vCAS) lte *..15.07
    • Sophos Unified Threat Management (UTM) Software eq 9.353..9.353

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    8.1

    Priority

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

    Source: NVD, CVSS v3

    8.1

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: CVE.org

    20.9 %

    EPSS score

    Elevated — model estimates 10-50% exploitation likelihood.

    Source: FIRST EPSS, percentile 97.6

    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
    116.63 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
    PoC (publicly reported)
    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
    8.1 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
    8.1
    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
    20.9 %
    Elevated — model estimates 10-50% 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
    97.6
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    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
    CISA assessment (SSVC)
    Exploitation: none known · not automatable · Technical impact: total
    Source: CISA Vulnrichment, as of 29 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-119

    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

    The (1) roaming_read and (2) roaming_write functions in roaming_common.c in the client in OpenSSH 5.x, 6.x, and 7.x before 7.1p2, when certain proxy and forward options are enabled, do not properly maintain connection file descriptors, which allows remote servers to cause a denial of service (heap-based buffer overflow) or possibly have unspecified other impact by requesting many forwardings.

    Source: NVD (NIST), cvelistv5

    Affected products

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

    Affected products
    Affected versionsFixed in
    openbsdopenssh
    • 6.0
    • 6.4
    • 5.8
    • 7.1
    • 5.7
    • 6.2
    • 6.5
    • 5.9
    • 6.3
    • 5.4
    • 6.7
    • 6.1
    • 6.9
    • 6.6
    • 5.5
    • 6.8
    • 7.0
    • 5.6
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    sophosunified_threat_management_software
    • 9.353
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxoraclelinux7
    macOSapplemac_os_x—
    Otheroraclesolaris11.3
    Otherhpvirtual_customer_access_system—

    Weakness classes (CWE)

    • CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer

      Class

      The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.

      Entry at MITRE CWE-119

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    Reference tagged as exploitopenwall.com (opens in a new tab)PoC (publicly reported)reported, not verified—
    Packet StormQualys Security Advisory OpenSSH Overflow Leak (opens in a new tab)packetstormsecurity.comPoC (publicly reported)reported, not verified—

    References & sources

    • blogs.sophos.com2016/02/17/utm-up2date-9-354-releasedRelease notes, Vendor advisory
    • lists.opensuse.orgSUSE-SU-2016:0117Vendor advisory, Mailing list, Third-party advisory
    • blogs.sophos.com2016/02/29/utm-up2date-9-319-releasedRelease notes, Vendor advisory
    • lists.apple.comAPPLE-SA-2016-03-21-5Vendor advisory, Mailing list, Release notes, Third-party advisory
    • h20566.www2.hpe.comportal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05247375Third-party advisory
    • securityfocus.com20160114 Qualys Security Advisory - Roaming through the OpenSSH client: CVE-2016-0777 and CVE-2016-0778Mailing list, Third-party advisory, Vulnerability database
    • support.apple.comHT206167Vendor advisory
    • lists.fedoraproject.orgFEDORA-2016-4556904561Vendor advisory, Mailing list, Third-party advisory
    • kb.juniper.netInfoCenter/index?page=content&id=JSA10734Third-party advisory
    • h20566.www2.hpe.comportal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05385680Third-party advisory
    • oracle.comtechnetwork/topics/security/linuxbulletinjan2016-2867209.htmlThird-party advisory
    • openssh.comtxt/release-7.1p2Patch, Release notes, Vendor advisory
    • lists.opensuse.orgopenSUSE-SU-2016:0128Vendor advisory, Mailing list, Third-party advisory
    • securityfocus.com80698Vulnerability database, Third-party advisory, Vulnerability database
    • lists.fedoraproject.orgFEDORA-2016-2e89eba0c1Vendor advisory, Mailing list, Third-party advisory
    • bto.bluecoat.comsecurity-advisory/sa109Third-party advisory
    • securitytracker.com1034671Vulnerability database, Third-party advisory, Vulnerability database
    • lists.opensuse.orgopenSUSE-SU-2016:0127Vendor advisory, Mailing list, Third-party advisory
    • security.gentoo.orgGLSA-201601-01Vendor advisory, Third-party advisory
    • h20566.www2.hpe.comportal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05390722Third-party advisory
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