CVE-2026-54886
published 2026-07-02CVE-2026-54886: Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in Erlang OTP ssh (ssh_sftpd module) allows an authenticated SFTP user to render an SFTP…
PriorityP423medium4.3CVSS 3.1
AVNACLPRLUINSUCNINAL
EPSS
0.33%
25.6th percentile
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.
Affected
10 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | erlang | — | — |
| erlang | erlang_otp | >= 17.0 < 27.3.4.14 | 27.3.4.14 |
| erlang | erlang_otp | >= 28.0 < 28.5.0.3 | 28.5.0.3 |
| erlang | erlang_otp | >= 29.0 < 29.0.3 | 29.0.3 |
| erlang | erlang_ssh | >= 3.0.1 < 5.2.11.9 | 5.2.11.9 |
| erlang | erlang_ssh | >= 5.3 < 5.5.2.2 | 5.5.2.2 |
| erlang | erlang_ssh | >= 6.0 < 6.0.2 | 6.0.2 |
| erlang | otp | >= 17.0 < * | * |
| erlang | otp | >= 3.0.1 < * | * |
| erlang | otp | >= 84adefa3318eef8631bf25cd233246a86eea18cd < eaf9550b8ad4738b81149d3f617102d980c6dd18 | eaf9550b8ad4738b81149d3f617102d980c6dd18 |
CVSS provenance
nvdv3.14.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
nvdv4.05.3MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/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
vendor_redhat5.3MEDIUM
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VulDB
Erlang OTP up to 3.0.0/6.0.1/16.x/29.0.2 SFTP Protocol ssh_sftpd.erl infinite loop
vuldb·2026-07-02·CVSS 5.3
CVE-2026-54886 [MEDIUM] Erlang OTP up to 3.0.0/6.0.1/16.x/29.0.2 SFTP Protocol ssh_sftpd.erl infinite loop
A vulnerability, which was classified as problematic, has been found in Erlang OTP up to 3.0.0/6.0.1/16.x/29.0.2. This affects an unknown part in the library lib/ssh/src/ssh_sftpd.erl of the component SFTP Protocol. The manipulation leads to infinite loop.
This vulnerability is documented as CVE-2026-54886. The attack requires being on the local network. There is not any exploit available.
It is advisable to upgrade the affected component.
Red Hat
erlang: Erlang OTP ssh: Denial of Service via infinite loop in SFTP channel
vendor_redhat·2026-07-02·CVSS 5.3
CVE-2026-54886 [MEDIUM] CWE-835 erlang: Erlang OTP ssh: Denial of Service via infinite loop in SFTP channel
erlang: Erlang OTP ssh: Denial of Service via infinite loop in SFTP channel
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,
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2026-54886 erlang: Erlang OTP ssh: Denial of Service via infinite loop in SFTP channel [epel-all]
bugzilla·2026-07-03·CVSS 5.3
CVE-2026-54886 [MEDIUM] CVE-2026-54886 erlang: Erlang OTP ssh: Denial of Service via infinite loop in SFTP channel [epel-all]
CVE-2026-54886 erlang: Erlang OTP ssh: Denial of Service via infinite loop in SFTP channel [epel-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
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 c
Bugzilla
CVE-2026-54886 erlang: Erlang OTP ssh: Denial of Service via infinite loop in SFTP channel [fedora-all]
bugzilla·2026-07-03·CVSS 5.3
CVE-2026-54886 [MEDIUM] CVE-2026-54886 erlang: Erlang OTP ssh: Denial of Service via infinite loop in SFTP channel [fedora-all]
CVE-2026-54886 erlang: Erlang OTP ssh: Denial of Service via infinite loop in SFTP channel [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
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
Bugzilla
CVE-2026-54886 erlang: Erlang OTP ssh: Denial of Service via infinite loop in SFTP channel
bugzilla·2026-07-02·CVSS 5.3
CVE-2026-54886 [MEDIUM] CVE-2026-54886 erlang: Erlang OTP ssh: Denial of Service via infinite loop in SFTP channel
CVE-2026-54886 erlang: Erlang OTP ssh: Denial of Service via infinite loop in SFTP channel
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
https://cna.erlef.org/cves/CVE-2026-54886.htmlhttps://github.com/erlang/otp/commit/eaf9550b8ad4738b81149d3f617102d980c6dd18https://github.com/erlang/otp/security/advisories/GHSA-7wp4-pc27-2vj9https://osv.dev/vulnerability/EEF-CVE-2026-54886https://www.erlang.org/doc/system/versions.html#order-of-versions
2026-07-02
Published