Is CVE-2026-62381 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-62381 being exploited in the wild.

How severe is CVE-2026-62381?

Medium severity, with a CVSS score of 6.6, published 22 August 2026.

Which products and versions are affected?

OpenWrt LuCI OpenWrt 18.06 through 25.12.

Is there a fix for CVE-2026-62381?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-62381 attacked?

It is attacked with local access, in a software library.

Am I affected by CVE-2026-62381?

Check whether you run OpenWrt LuCI at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-62381: OpenWrt LuCI heap buffer overflow in ASN.1 certificate signing

CVE-2026-62381 · Severity: medium · CVSS 6.6 · Published 2026-08-22

LuCI is the web-based configuration interface for OpenWrt routers and network devices. The underlying luci-lib-px5g library contains a heap buffer overflow when generating digital certificates with 2040-bit RSA keys. An attacker with local access to the LuCI application or control over certificate generation parameters could trigger a memory corruption, potentially leading to service disruption or code execution depending on how the application embedding LuCI uses this functionality.

Technologies: OpenWrt LuCI. Vendors: OpenWrt.

Quick answers

Is CVE-2026-62381 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-62381 being exploited in the wild.
How severe is CVE-2026-62381?: Medium severity, with a CVSS score of 6.6, published 22 August 2026.
Which products and versions are affected?: OpenWrt LuCI OpenWrt 18.06 through 25.12.
Is there a fix for CVE-2026-62381?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-62381 attacked?: It is attacked with local access, in a software library.
Am I affected by CVE-2026-62381?: Check whether you run OpenWrt LuCI at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability is a heap-based buffer overflow in the ASN.1 encoding routine asn1_add_obj() within x509write.c. When signing a certificate with a 2040-bit RSA key (producing a 255-byte signature), the code miscalculates the allocation size for a BIT STRING structure. It computes the DER length encoding for 255 bytes but then writes 256 bytes (after prepending the unused-bits byte), requiring one additional DER length octet. This causes a 1-byte write beyond the allocated 259-byte heap buffer. The overflow is reachable through the public Lua API via create_selfsigned(), making it accessible if an application exposes certificate signing operations to untrusted callers. The vulnerability affects OpenWrt release branches 18.06 through 25.12; it has been removed (not patched) from the master branch.

Affected products

OpenWrt LuCI OpenWrt 18.06 through 25.12

Timeline

2026-08-22: disclosed
2026-08-07: advisory: GitHub Security Advisory GHSA-jgc3-4q3p-g6xh published

References

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