MediumCVE-2026-54891

    Erlang OTP: Improper Enforcement of Message Integrity During Transmission in a Communication Channel (CVE-2026-54891)

    Published Last modified Sources: SUSE, Debian, BSI, CVE.org, OSV, Msrc Update Guide

    What is affected, what to do

    Improper Enforcement of Message Integrity During Transmission in a Communication Channel vulnerability in Erlang/OTP ssl (tls_gen_connection module) allows a network-positioned attacker to inject unauthenticated plaintext that the TLS client application later treats as authenticated server data. The function tls_gen_connection:handle_protocol_record/3 rejects APPLICATION_DATA records that arrive in pre-handshake states when the TLS endpoint acts as a server, but does not apply the same check when the endpoint acts as a client.

    Update Erlang OTP to version 27.3.4.14, Erlang OTP to version 28.5.0.3, Erlang OTP to version 29.0.3.

    Affected
    • Erlang OTP lt 17.0..27.3.4.14
    • Erlang OTP lt 28.0..28.5.0.3
    • Erlang OTP lt 29.0..29.0.3
    • Erlang OTP lt 5.3.4..11.2.12.10
    • Erlang OTP lt 11.3..11.6.0.3
    • Erlang OTP lt 11.7..11.7.3
    Fixed in
    • Erlang OTP 27.3.4.14
    • Erlang OTP 28.5.0.3
    • Erlang OTP 29.0.3
    • Erlang OTP 11.2.12.10
    • Erlang OTP 11.6.0.3
    • Erlang OTP 11.7.3

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

    Metrics

    6.3

    Priority

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

    Source: NVD, CVSS v4

    3.7

    CVSS v3

    Severity Low on the scale from 0 to 10.

    Source: SUSE, Debian, BSI, CVE.org, OSV, Msrc Update Guide

    0.1 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 3.0

    Show all metrics
    Severity
    Medium
    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
    51.30 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
    6.3 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
    3.7
    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
    6.3
    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
    0.1 %
    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
    3.0
    Low — this CVE sits in the lower 10% of all CVEs scored today.
    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: partial
    Source: CISA Vulnrichment, as of 2 July 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-924

    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
    Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
    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

    Improper Enforcement of Message Integrity During Transmission in a Communication Channel vulnerability in Erlang/OTP ssl (tls_gen_connection module) allows a network-positioned attacker to inject unauthenticated plaintext that the TLS client application later treats as authenticated server data. The function tls_gen_connection:handle_protocol_record/3 rejects APPLICATION_DATA records that arrive in pre-handshake states when the TLS endpoint acts as a server, but does not apply the same check when the endpoint acts as a client. A network-positioned attacker can send plaintext APPLICATION_DATA records to the client during the handshake. The records are buffered and, once the handshake completes successfully, delivered to the application as if they were authenticated post-handshake data. The attacker cannot observe the client's response or steer the connection, so the impact is limited to blind injection of unauthenticated bytes. The injection window is wider for TLS versions prior to TLS 1.3 than for TLS 1.3. This vulnerability is associated with program file lib/ssl/src/tls_gen_connection.erl. TLS 1.3 is affected starting with OTP 22.0, when TLS 1.3 support was added. This issue affects OTP from OTP 17.0 before OTP 27.3.4.14, from OTP 28.0 before OTP 28.5.0.3, and from OTP 29.0 before OTP 29.0.3, corresponding to ssl from 5.3.4 before 11.2.12.10, from 11.3 before 11.6.0.3, and from 11.7 before 11.7.3. Whether OTP before OTP 17.0, corresponding to ssl before 5.3.4, is affected is unknown.

    Source: suse_csaf, Debian Security Advisories, BSI WID Portal, BSI CSAF, NVD (NIST), OSV (Open Source Vulnerabilities), cvelistv5, Microsoft Security Update Guide

    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
    ErlangOTP
    • 11.7 – < 11.7.3
    • 11.3 – < 11.6.0.3
    • 5.3.4 – < 11.2.12.10
    • 29.0 – < 29.0.3
    • 28.0 – < 28.5.0.3
    • 17.0 – < 27.3.4.14
    • 11.7.3
    • 11.6.0.3
    • 11.2.12.10
    • 29.0.3
    • 28.5.0.3
    • 27.3.4.14
    erlangerlang\/otp
    • 28.0 – < 28.5.0.3
    • 17.0 – < 27.3.4.14
    • 29.0 – < 29.0.3
    • 28.5.0.3
    • 27.3.4.14
    • 29.0.3
    erlangerlang\/ssl
    • 11.7 – < 11.7.3
    • 11.3 – < 11.6.0.3
    • 5.3.4 – < 11.2.12.10
    • 11.7.3
    • 11.6.0.3
    • 11.2.12.10
    Open SourceErlang/OTP
    • < 29.0.3
    • < 28.5.0.3
    • < 27.3.4.14
    • 29.0.3
    • 28.5.0.3
    • 27.3.4.14

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianerlangtrixie

    Weakness classes (CWE)

    • CWE-924Improper Enforcement of Message Integrity During Transmission in a Communication Channel

      Base

      The product establishes a communication channel with an endpoint and receives a message from that endpoint, but it does not sufficiently ensure that the message was not modified during transmission.

      Entry at MITRE CWE-924

    References & sources

    • github.comerlang/otp/security/advisories/GHSA-gf6r-99xw-6qg6advisory, Vendor advisory, related, Vendor advisory
    • cna.erlef.orgcves/CVE-2026-54891.htmlweb, related, Vendor advisory
    • erlang.orgdoc/system/versions.htmlweb, x_version-scheme, Release notes
    • github.comerlang/otp/commit/07d2d0e93f6aaf7652a81e8df075fc1728da5e96fix, Patch, Patch
    • OSV (Open Source Vulnerabilities)vulnerability/EEF-CVE-2026-54891related, Third-party advisory

    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. Record modifiedEEF

      1 individual change: Affected versions (publisher)

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/54xxx/CVE-2026-54891.json">CVE-2026-54891</a>

      Source identifier: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

    2. Record modifiedEEF

      Description added or changed

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)changed
      OTP, OTP
      OTP, OTP, OTP
      Descriptionchanged
      Improper Enforcement of Message Integrity During Transmission in a Communication Channel vulnerability in Erlang/OTP ssl (tls_gen_connection module) allows a network-positioned attacker to inject unauthenticated plaintext that the TLS client application later treats as authenticated server data. The function tls_gen_connection:handle_protocol_record/3 rejects APPLICATION_DATA records that arrive in pre-handshake states when the TLS endpoint acts as a server, but does not apply the same check when the endpoint acts as a client. A network-positioned attacker can send plaintext APPLICATION_DATA records to the client during the handshake. The records are buffered and, once the handshake completes successfully, delivered to the application as if they were authenticated post-handshake data. The attacker cannot observe the client's response or steer the connection, so the impact is limited to blind injection of unauthenticated bytes. The injection window is wider for TLS versions prior to TLS 1.3 than for TLS 1.3. This vulnerability is associated with program file lib/ssl/src/tls_gen_connection.erl. This issue affects OTP from OTP 17.0 before OTP 29.0.3, OTP 28.5.0.3 and OTP 27.3.4.14, corresponding to ssl from 5.3.4 before 11.7.3, 11.6.0.3 and 11.2.12.10. TLS 1.3 is affected starting with OTP 22.0, when TLS 1.3 support was added.
      Improper Enforcement of Message Integrity During Transmission in a Communication Channel vulnerability in Erlang/OTP ssl (tls_gen_connection module) allows a network-positioned attacker to inject unauthenticated plaintext that the TLS client application later treats as authenticated server data. The function tls_gen_connection:handle_protocol_record/3 rejects APPLICATION_DATA records that arrive in pre-handshake states when the TLS endpoint acts as a server, but does not apply the same check when the endpoint acts as a client. A network-positioned attacker can send plaintext APPLICATION_DATA records to the client during the handshake. The records are buffered and, once the handshake completes successfully, delivered to the application as if they were authenticated post-handshake data. The attacker cannot observe the client's response or steer the connection, so the impact is limited to blind injection of unauthenticated bytes. The injection window is wider for TLS versions prior to TLS 1.3 than for TLS 1.3. This vulnerability is associated with program file lib/ssl/src/tls_gen_connection.erl. TLS 1.3 is affected starting with OTP 22.0, when TLS 1.3 support was added. This issue affects OTP from OTP R13B03 before OTP 27.3.4.14, from OTP 28.0 before OTP 28.5.0.3, and from OTP 29.0 before OTP 29.0.3, corresponding to ssl from 3.10.7 before 11.2.12.10, from 11.3 before 11.6.0.3, and from 11.7 before 11.7.3. Whether OTP before OTP R13B03, corresponding to ssl before 3.10.7, is affected is unknown.

      Source identifier: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

    3. Record modifiedEEF

      Description added or changed

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionchanged
      Improper Enforcement of Message Integrity During Transmission in a Communication Channel vulnerability in Erlang/OTP ssl (tls_gen_connection module) allows a network-positioned attacker to inject unauthenticated plaintext that the TLS client application later treats as authenticated server data. The function tls_gen_connection:handle_protocol_record/3 rejects APPLICATION_DATA records that arrive in pre-handshake states when the TLS endpoint acts as a server, but does not apply the same check when the endpoint acts as a client. A network-positioned attacker can send plaintext APPLICATION_DATA records to the client during the handshake. The records are buffered and, once the handshake completes successfully, delivered to the application as if they were authenticated post-handshake data. The attacker cannot observe the client's response or steer the connection, so the impact is limited to blind injection of unauthenticated bytes. The injection window is wider for TLS versions prior to TLS 1.3 than for TLS 1.3. This vulnerability is associated with program file lib/ssl/src/tls_gen_connection.erl. This issue affects OTP from OTP 17.0 before 29.0.3, 28.5.0.3 and 27.3.4.14 corresponding to ssl from 5.3.4 before 11.7.3, 11.6.0.3 and 11.2.12.10. TLS 1.3 is affected starting with OTP 22.0, when TLS 1.3 support was added.
      Improper Enforcement of Message Integrity During Transmission in a Communication Channel vulnerability in Erlang/OTP ssl (tls_gen_connection module) allows a network-positioned attacker to inject unauthenticated plaintext that the TLS client application later treats as authenticated server data. The function tls_gen_connection:handle_protocol_record/3 rejects APPLICATION_DATA records that arrive in pre-handshake states when the TLS endpoint acts as a server, but does not apply the same check when the endpoint acts as a client. A network-positioned attacker can send plaintext APPLICATION_DATA records to the client during the handshake. The records are buffered and, once the handshake completes successfully, delivered to the application as if they were authenticated post-handshake data. The attacker cannot observe the client's response or steer the connection, so the impact is limited to blind injection of unauthenticated bytes. The injection window is wider for TLS versions prior to TLS 1.3 than for TLS 1.3. This vulnerability is associated with program file lib/ssl/src/tls_gen_connection.erl. This issue affects OTP from OTP 17.0 before OTP 29.0.3, OTP 28.5.0.3 and OTP 27.3.4.14, corresponding to ssl from 5.3.4 before 11.7.3, 11.6.0.3 and 11.2.12.10. TLS 1.3 is affected starting with OTP 22.0, when TLS 1.3 support was added.

      Source identifier: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

    4. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: none known, automatable: no

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      SSVC assessmentadded
      —
      {"id":"CVE-2026-54891","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-07-02T17:24:44.468465Z"}

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

    5. ReceivedEEF

      CVSS V4.0: AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

      Weakness type: CWE-924

      Description added or changed

      Show 9 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      OTP, OTP
      Descriptionadded
      —
      Improper Enforcement of Message Integrity During Transmission in a Communication Channel vulnerability in Erlang/OTP ssl (tls_gen_connection module) allows a network-positioned attacker to inject unauthenticated plaintext that the TLS client application later treats as authenticated server data. The function tls_gen_connection:handle_protocol_record/3 rejects APPLICATION_DATA records that arrive in pre-handshake states when the TLS endpoint acts as a server, but does not apply the same check when the endpoint acts as a client. A network-positioned attacker can send plaintext APPLICATION_DATA records to the client during the handshake. The records are buffered and, once the handshake completes successfully, delivered to the application as if they were authenticated post-handshake data. The attacker cannot observe the client's response or steer the connection, so the impact is limited to blind injection of unauthenticated bytes. The injection window is wider for TLS versions prior to TLS 1.3 than for TLS 1.3. This vulnerability is associated with program file lib/ssl/src/tls_gen_connection.erl. This issue affects OTP from OTP 17.0 before 29.0.3, 28.5.0.3 and 27.3.4.14 corresponding to ssl from 5.3.4 before 11.7.3, 11.6.0.3 and 11.2.12.10. TLS 1.3 is affected starting with OTP 22.0, when TLS 1.3 support was added.
      CVSSadded
      —
      AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
      Weakness type (CWE)added
      —
      CWE-924
      Referenceadded
      —
      https://cna.erlef.org/cves/CVE-2026-54891.html
      Referenceadded
      —
      https://github.com/erlang/otp/commit/07d2d0e93f6aaf7652a81e8df075fc1728da5e96
      Referenceadded
      —
      https://github.com/erlang/otp/security/advisories/GHSA-gf6r-99xw-6qg6
      Referenceadded
      —
      https://osv.dev/vulnerability/EEF-CVE-2026-54891
      Referenceadded
      —
      https://www.erlang.org/doc/system/versions.html#order-of-versions

      Source identifier: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

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