Unreal Engine 5.8 Linux Crash Report (CEF/NSS PKCS#11 Segfault)

Development Getting Started & Setup
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Summary

Unreal Engine 5.8 on Linux crashes immediately during startup when reaching the Welcome Window / Online Services initialization stage. The crash occurs consistently with a segmentation fault inside NSS/CEF when a PKCS#11 module (onepin-opensc-pkcs11.so) is loaded.

The issue does not occur in Unreal Engine 5.6.1 on the same system, suggesting a regression in 5.8 related to CEF/NSS initialization or OpenSSL interaction.

System Information

  • OS: Debian 13 (Trixie)

  • Kernel: (you can fill this in)

  • Session: X11 (echo $XDG_SESSION_TYPE = x11)

  • GPU: NVIDIA (Driver: 590.48.01, CUDA 13.1)

  • Unreal Engine: 5.8 (crashes), 5.6.1 (works mostly stable)

  • Display Server: X11 (Wayland not in use)

Crash Description

Crash happens during startup at:

Preloader → Welcome Window → Online Services / Login initialization

Immediately after this stage, the editor exits with:

Caught signal 11 (Segmentation fault)

Crash Stack Trace

libUnrealEditor-DerivedDataCache.so
  → OPENSSL_LH_retrieve
libcrypto.so.3
libcrypto.so.3
libcrypto.so.3
OSSL_LIB_CTX_new
libopensc.so.12
onepin-opensc-pkcs11.so → C_Initialize
libnss3.so
libnss3.so
SECMOD_LoadModule
NSS_InitReadWrite
libcef.so

Observations

  • The crash is triggered during CEF (Chromium Embedded Framework) initialization.

  • NSS loads system PKCS#11 modules automatically.

  • A third-party module is loaded:

/usr/lib/x86_64-linux-gnu/onepin-opensc-pkcs11.so
  • This module comes from:
opensc-pkcs11 (OpenSC smartcard framework 0.26)
  • The crash disappears after removing this module from NSS database:
modutil -dbdir sql:$HOME/.pki/nssdb \
-delete "OpenSC smartcard framework (0.26)"

Root Cause (suspected)

It appears that Unreal Engine 5.8 CEF initialization triggers NSS to load all registered PKCS#11 modules.

If a system-installed module (OpenSC onepin) is present, it causes a segmentation fault during initialization.

This does not appear to be handled safely by CEF/NSS, resulting in a full editor crash.

Temporary Workaround

The crash can be avoided by removing the OpenSC PKCS#11 module from the user’s NSS database, which prevents NSS/CEF from loading the problematic library during Unreal Engine startup.



modutil -dbdir sql:$HOME/.pki/nssdb \
-delete "OpenSC smartcard framework (0.26)"

After applying this change, Unreal Engine 5.8 starts normally without crashing during the Welcome Window / Online Services initialization phase.

This workaround confirms that the crash is triggered by the interaction between NSS/CEF and the OpenSC PKCS#11 module, rather than Unreal Engine core systems.

Rollback (Restoring the Original State)

If smart card or PKCS#11 functionality is required later, the module can be re-added to the NSS database as follows:



modutil -dbdir sql:$HOME/.pki/nssdb \
-add "OpenSC smartcard framework (0.26)" \
-libfile /usr/lib/x86_64-linux-gnu/onepin-opensc-pkcs11.so

Verify that the module has been restored:



modutil -dbdir sql:$HOME/.pki/nssdb -list

After rollback, any applications relying on PKCS#11 (e.g., smart cards, tokens, or authentication devices) will function normally again.

Impact

  • Blocks Unreal Engine 5.8 startup on Linux systems with OpenSC PKCS#11 installed.

  • Affects systems even if smart cards are not actively used.

  • Requires manual NSS database modification to workaround.

Request

Please investigate:

  • Why CEF/NSS initialization in UE 5.8 is loading system PKCS#11 modules

  • Why OpenSC onepin-opensc-pkcs11.so causes a segmentation fault instead of being safely ignored

  • Whether module loading can be sandboxed or disabled during Unreal Engine startup

Reproducibility

100% reproducible on Debian 13 with NVIDIA drivers when OpenSC PKCS#11 module is present in NSS database.