CVE-2026-57166 PJSIP: Pre-authentication overflow in the telnet CLI error
A stack buffer overflow in the PJSIP telnet CLI can cause application termination when processing long commands, affecting only applications with the unauthenticated CLI enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-57166?
CVE-2026-57166 is a medium-severity memory corruption vulnerability in pjsip pjproject, published on 4 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
PJSIP is a free and open source multimedia communication library written in C. Prior to commit 4472a31, a stack buffer overflow exists in the PJLIB-UTIL telnet CLI front-end when rendering feedback for an entered command line. Several command-line handling paths write an attacker-influenced amount of data into fixed-size buffers without sufficient bounds checking, so a long command line can overflow them. This affects only applications that enable the telnet CLI front-end (e.g. pj_cli_telnet_create() / --cli-telnet-port). The telnet CLI is an interactive administration interface with no authentication, so any client able to reach it can already issue arbitrary CLI commands. A malformed or overly long command line can overflow a fixed-size stack buffer while rendering command-line feedback, which may lead to application termination. Because reaching this code already requires access to the unauthenticated CLI, the impact beyond that existing access is limited. Applications that do not enable the telnet CLI front-end are not affected. This issue has been patched via commit 4472a31.
Weakness: CWE-121
Which versions are affected by CVE-2026-57166?
It affects 1 product.
Products include Teluu Pjsip.
How do I fix CVE-2026-57166?
No fix has been published for CVE-2026-57166 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-57166 being exploited?
There is no known exploitation of CVE-2026-57166 in the wild and no public exploit code.
Other vulnerabilities in pjsip pjproject
- CVE-2023-38703 PJSIP has use-after-free vulnerability in SRTP media transport
- CVE-2022-39269 Media transport downgrade from the secure version (SRTP) to non-secure (RTP) in pjsip
- CVE-2026-57161 PJSIP: Stack overflow handling Service-Route headers in a registration response
- CVE-2026-57162 PJSIP: Stack overflow parsing SDP a=crypto attributes
- CVE-2026-57163 PJSIP: Stack overflow parsing a TLS peer certificate's SubjectAltName in GnuTLS backend
Sources
Also known as DEBIAN-CVE-2026-57166, GHSA-9c8q-h38q-p85j, UBUNTU-CVE-2026-57166.