CVE-2026-62381 openwrt CVE debrief

Who should care

OpenWRT administrators and developers using luci-lib-px5g, especially those with remote access to the Lua interface, should assess their exposure and prioritize patching. They should review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance. They should also plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.

Why it matters

CVE-2026-62381 is a MEDIUM-severity vulnerability in luci-lib-px5g that can lead to heap-based buffer overflows when signing certificates with 2040-bit RSA keys. OpenWRT deployments using this library, especially with remote Lua interface access, should assess exposure and prioritize patching.

• Remote code execution may be possible depending on the embedding application
• Potential for denial-of-service (DoS) attacks
• Elevation of privileges may be achievable
• Data tampering or unauthorized access could occur

Technical summary

The vulnerability exists in the asn1_add_obj function in x509write.c, which is part of the luci-lib-px5g package. When signing a certificate with a 2040-bit RSA key, a heap-based buffer overflow occurs due to incorrect allocation and memcpy operations. The vulnerable code is present on the openwrt-18.06 through openwrt-25.12 release branches and is absent from master, where the luci-lib-px5g package has been removed rather than patched. The overflow is reachable through the exported Lua interface via create_selfsigned(); whether it is remotely exploitable depends on the embedding application.

Defensive priority

Assess exposure and prioritize patching for OpenWRT deployments using luci-lib-px5g, especially those with remote access to the Lua interface.

Recommended defensive actions

• Assess OpenWRT deployments for exposure to CVE-2026-62381
• Prioritize patching for deployments with remote access to the Lua interface
• Monitor for potential remote exploitation attempts
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE and NVD records provide details on the vulnerability, including its CVSS score of 6.9 and MEDIUM severity. The vulnerability is caused by a heap-based buffer overflow in the asn1_add_obj function.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.