CriticalCVE-2026-34182

    CMS AuthEnvelopedData Processing May Accept Forged Messages (CVE-2026-34182)

    Published Last modified Sources: SingCERT, Red Hat, SUSE, Ubuntu, Debian, CVE.org, Msrc Update Guide, BSI

    What is affected, what to do

    A flaw was found in OpenSSL's Cryptographic Message Services (CMS) AuthEnvelopedData processing. An on-path attacker can exploit insufficient input validation on cipher and tag length fields by sending specially crafted CMS messages.

    Update OpenSSL to version 4.0.1, OpenSSL to version 3.6.3, OpenSSL to version 3.5.7.

    Affected
    • OpenSSL lt 4.0.0..4.0.1
    • OpenSSL lt 3.6.0..3.6.3
    • OpenSSL lt 3.5.0..3.5.7
    • OpenSSL lt 3.4.0..3.4.6
    • OpenSSL lt 3.0.0..3.0.21
    Fixed in
    • OpenSSL 4.0.1
    • OpenSSL 3.6.3
    • OpenSSL 3.5.7
    • OpenSSL 3.4.6
    • OpenSSL 3.0.21

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

    Metrics

    9.1

    Priority

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

    Source: NVD, CVSS v3

    9.1

    CVSS v3

    Severity Critical on the scale from 0 to 10.

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

    1.1 %

    EPSS score

    Moderate — model estimates 1-10% exploitation likelihood.

    Source: FIRST EPSS, percentile 64.3

    Show all metrics
    Severity
    Critical
    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
    97.27 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
    9.1 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
    9.1
    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
    1.1 %
    Moderate — model estimates 1-10% 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
    64.3
    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
    CISA assessment (SSVC)
    Exploitation: none known · automatable · Technical impact: partial
    Source: CISA Vulnrichment, as of 10 June 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-354

    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 flaw was found in OpenSSL's Cryptographic Message Services (CMS) AuthEnvelopedData processing. An on-path attacker can exploit insufficient input validation on cipher and tag length fields by sending specially crafted CMS messages. This can lead to the forging of messages or bypassing integrity validation. Consequently, an attacker may achieve key-equivalent functionality for a given CMS recipient.

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

    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
    OpenSSLOpenSSL
    • 3.4.0 – < 3.4.6
    • 3.0.0 – < 3.0.21
    • 4.0.0 – < 4.0.1
    • 3.6.0 – < 3.6.3
    • 3.5.0 – < 3.5.7
    • 3.4.6
    • 3.0.21
    • 4.0.1
    • 3.6.3
    • 3.5.7
    opensslopenssl
    • 3.6.0 – < 3.6.3
    • 3.0.0 – < 3.0.21
    • 3.5.0 – < 3.5.7
    • 3.4.0 – < 3.4.6
    • 4.0.0
    • 3.6.3
    • 3.0.21
    • 3.5.7
    • 3.4.6
    • —
    IBMApp Connect Enterprise CD
    • < 13.4.0
    • 13.4.0
    IBMApp Connect Enterprise LTS
    • < 13.4.0
    • < 12.0.26
    • 13.4.0
    • 12.0.26
    Open SourceOpenSSL
    • < 3.4.6
    • < 1.0.2zq
    • < 4.0.1
    • < 3.6.3
    • < 3.0.21
    • < 1.1.1zh
    • 3.4.6
    • 1.0.2zq
    • 4.0.1
    • 3.6.3
    • 3.0.21
    • 1.1.1zh
    OracleSolaris
    • <11.3 ESU 36.36
    • <11.4 SRU 94
    • —
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianopensslbookworm
    Linuxdebianopenssltrixie

    Weakness classes (CWE)

    • CWE-354Improper Validation of Integrity Check Value

      Base

      The product does not validate or incorrectly validates the integrity check values or "checksums" of a message. This may prevent it from detecting if the data has been modified or corrupted in transmission.

      Entry at MITRE CWE-354

    References & sources

    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).

    1. Initial analysis by NVDNVD

      Newly listed as affected:
      • OpenSSL (3.0.0 – before 3.0.21; 3.4.0 – before 3.4.6; 3.5.0 – before 3.5.7; 3.6.0 – before 3.6.3; 1 individual version)
      Show 7 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Product configurationadded
      —
      OR *cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* versions from (including) 3.0.0 up to (excluding) 3.0.21 *cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* versions from (including) 3.4.0 up to (excluding) 3.4.6 *cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* versions from (including) 3.5.0 up to (excluding) 3.5.7 *cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* versions from (including) 3.6.0 up to (excluding) 3.6.3 *cpe:2.3:a:openssl:openssl:4.0.0:-:*:*:*:*:*:*
      Reference typeadded
      —
      OpenSSL Software Foundation: https://github.com/openssl/openssl/commit/03c1f4d45fb963aee7d5833390c507cd290182bc Types: Patch
      Reference typeadded
      —
      OpenSSL Software Foundation: https://github.com/openssl/openssl/commit/439ed7d2c0962ce964482727264668bf277c333f Types: Patch
      Reference typeadded
      —
      OpenSSL Software Foundation: https://github.com/openssl/openssl/commit/7947e6a81eb8776802f159fb6762cb7fcf7e34c7 Types: Patch
      Reference typeadded
      —
      OpenSSL Software Foundation: https://github.com/openssl/openssl/commit/9fd97f8cfdc2c0be214998de3b2b55c8edf6c7ac Types: Patch
      Reference typeadded
      —
      OpenSSL Software Foundation: https://github.com/openssl/openssl/commit/d2ca86bcd43e4f17d899f347101766b6107676e0 Types: Patch
      Reference typeadded
      —
      OpenSSL Software Foundation: https://openssl-library.org/news/secadv/20260609.txt Types: Vendor Advisory

      Source identifier: nvd@nist.gov

    2. Record modifiedopenssl.org

      Show 10 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://github.com/openssl/openssl/commit/03c1f4d45fb963aee7d5833390c507cd290182bc
      Referenceadded
      —
      https://github.com/openssl/openssl/commit/439ed7d2c0962ce964482727264668bf277c333f
      Referenceadded
      —
      https://github.com/openssl/openssl/commit/7947e6a81eb8776802f159fb6762cb7fcf7e34c7
      Referenceadded
      —
      https://github.com/openssl/openssl/commit/9fd97f8cfdc2c0be214998de3b2b55c8edf6c7ac
      Referenceadded
      —
      https://github.com/openssl/openssl/commit/d2ca86bcd43e4f17d899f347101766b6107676e0
      Referenceremoved
      https://github.com/openssl/security/commit/03c1f4d45fb963aee7d5833390c507cd290182bc
      —
      Referenceremoved
      https://github.com/openssl/security/commit/439ed7d2c0962ce964482727264668bf277c333f
      —
      Referenceremoved
      https://github.com/openssl/security/commit/7947e6a81eb8776802f159fb6762cb7fcf7e34c7
      —
      Referenceremoved
      https://github.com/openssl/security/commit/9fd97f8cfdc2c0be214998de3b2b55c8edf6c7ac
      —
      Referenceremoved
      https://github.com/openssl/security/commit/d2ca86bcd43e4f17d899f347101766b6107676e0
      —

      Source identifier: openssl-security@openssl.org

    One NVD translation into another language is hidden.

    Linked advisories

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