Deserialization of Untrusted Data in Symfony - CVE-2026-45077
Published: May 21, 2026
Vulnerability identifier: #VU132061
CSH Severity: High
CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-45077
CWE-ID: CWE-502
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code or cause a denial of service.
The vulnerability exists due to deserialization of untrusted data in Symfony\Bridge\Monolog\Command\ServerLogCommand when processing messages received by the server:log TCP listener. A remote attacker can send a specially crafted serialized payload to execute arbitrary code or cause a denial of service.
Exploitation requires the server:log command to be running and reachable on TCP port 9911. Code execution is environment-dependent on the presence of usable gadget chains in the target process.
Affected software
Symfony
Debian Linux
symfony (Debian package)
Debian Linux
symfony (Debian package)
How to mitigate CVE-2026-45077
Install security update from vendor's website.
Symfony - addressed in versions 5.4.52, 6.4.40, 7.4.12, 8.0.12
symfony (Debian package) - addressed in versions 5.4.53+dfsg-0+deb12u1, 6.4.41+dfsg-0+deb13u1
symfony (Debian package) - addressed in versions 5.4.53+dfsg-0+deb12u1, 6.4.41+dfsg-0+deb13u1