Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in Erlang OTP ssh (ssh_sftpd module) allows an authenticated SFTP user to render an SFTP channel permanently unresponsive. The handle_data/4 function in ssh_sftpd contains a catch-all clause that accepts channel data of any type. When channel data with a non-zero type code (SSH_MSG_CHANNEL_EXTENDED_DATA) arrives with an empty pending buffer and a payload at or below the SFTP packet size limit, the clause tail-calls itself with identical arguments, creating an infinite loop. The SFTP protocol operates exclusively on normal channel data (type 0). Extended data (non-zero type) is meaningless for SFTP and is never sent by conforming clients. However, the SSH protocol permits any channel participant to send extended data on an open channel, so an authenticated SFTP client can trigger the loop by sending SSH_MSG_CHANNEL_EXTENDED_DATA with any data_type_code and any non-empty payload at or below the size limit. The targeted ssh_sftpd process enters an infinite tail-recursive loop. It never processes another message, its message queue grows without bound, and it can only be stopped by killing the process. BEAM's reduction-based scheduler preemption continues to function, so other processes on the node are not starved, but each stuck channel process consumes its full CPU time share continuously and accumulates unbounded message queue memory. Opening many channels amplifies the CPU and memory impact. Erlang/OTP SSH configurations using the default max_channels setting (infinity) allow an authenticated user to open unlimited channels per connection, amplifying the attack without requiring multiple TCP connections or authentications. No file contents, credentials, or write access are obtainable through this issue. The impact is limited to denial of service on targeted SFTP channels, with secondary CPU degradation and memory growth. This vulnerability is associated with program file lib/ssh/src/ssh_sftpd.erl and program routine ssh_sftpd:handle_data/4. 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 ssh from 3.0.1 before 6.0.2, 5.5.2.2 and 5.2.11.9.

The remote Fedora 43 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-965be97ac0 advisory.

    Backport fixes for CVE-2026-48858 (ftp SSRF), CVE-2026-49759 (SCTP DoS), CVE-2026-48860 (dist-over-TLS     auth bypass), CVE-2026-54886 (ssh SFTP DoS), CVE-2026-54891 (TLS handshake data injection), and     CVE-2026-55952 (TLS 1.3 session ticket DoS). These are fixed upstream in OTP 27.x (rawhide/f45);
    backported here to the OTP 26.x line.

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Fedora 44 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-dcf80dc1ff advisory.

    Backport fixes for CVE-2026-48858 (ftp SSRF), CVE-2026-49759 (SCTP DoS), CVE-2026-48860 (dist-over-TLS     auth bypass), CVE-2026-54886 (ssh SFTP DoS), CVE-2026-54891 (TLS handshake data injection), and     CVE-2026-55952 (TLS 1.3 session ticket DoS). These are fixed upstream in OTP 27.x (rawhide/f45);
    backported here to the OTP 26.x line.

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of Erlang/OTP installed on the remote host is 17.0 prior to 27.3.4.14, 28.0 prior to 28.5.0.3, or 29.0 prior to 29.0.3. It is, therefore, affected by multiple vulnerabilities:

  - Observable Response Discrepancy vulnerability in Erlang OTP ssh (ssh_sftpd module) allows an authenticated     SFTP user to enumerate the existence of files and directories outside the configured root directory.
    (CVE-2026-53422)

  - Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in Erlang OTP ssh (ssh_sftpd module)     allows an authenticated SFTP user to render an SFTP channel permanently unresponsive. (CVE-2026-54886)

  - 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. (CVE-2026-54891)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in Erlang OTP ssh (ssh_sftpd module)     allows an authenticated SFTP user to render an SFTP channel permanently unresponsive. The handle_data/4     function in ssh_sftpd contains a catch-all clause that accepts channel data of any type. When channel data     with a non-zero type code (SSH_MSG_CHANNEL_EXTENDED_DATA) arrives with an empty pending buffer and a     payload at or below the SFTP packet size limit, the clause tail-calls itself with identical arguments,     creating an infinite loop. The SFTP protocol operates exclusively on normal channel data (type 0).
    Extended data (non-zero type) is meaningless for SFTP and is never sent by conforming clients. However,     the SSH protocol permits any channel participant to send extended data on an open channel, so an     authenticated SFTP client can trigger the loop by sending SSH_MSG_CHANNEL_EXTENDED_DATA with any     data_type_code and any non-empty payload at or below the size limit. The targeted ssh_sftpd process enters     an infinite tail-recursive loop. It never processes another message, its message queue grows without     bound, and it can only be stopped by killing the process. BEAM's reduction-based scheduler preemption     continues to function, so other processes on the node are not starved, but each stuck channel process     consumes its full CPU time share continuously and accumulates unbounded message queue memory. Opening many     channels amplifies the CPU and memory impact. Erlang/OTP SSH configurations using the default max_channels     setting (infinity) allow an authenticated user to open unlimited channels per connection, amplifying the     attack without requiring multiple TCP connections or authentications. No file contents, credentials, or     write access are obtainable through this issue. The impact is limited to denial of service on targeted     SFTP channels, with secondary CPU degradation and memory growth. This vulnerability is associated with     program file lib/ssh/src/ssh_sftpd.erl and program routine ssh_sftpd:handle_data/4. This issue affects OTP     from OTP 17.0 until OTP 29.0.3, 28.5.0.3, and 27.3.4.14 corresponding to ssh from 3.0.1 until 6.0.2,     5.5.2.2, and 5.2.11.9. (CVE-2026-54886)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
327809	Fedora 43 : erlang (2026-965be97ac0)	Nessus	Fedora Local Security Checks	high
327806	Fedora 44 : erlang (2026-dcf80dc1ff)	Nessus	Fedora Local Security Checks	high
325890	Erlang/OTP 17.0 < 27.3.4.14 / 28.0 < 28.5.0.3 / 29.0 < 29.0.3 Multiple Vulnerabilities	Nessus	Misc.	medium
324944	Linux Distros Unpatched Vulnerability : CVE-2026-54886	Nessus	Misc.	medium

Detections

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CVE-2026-54886

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Tenable Plugins

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