luci-lib-px5g 2040-bit Certificate Signing Heap Buffer Overflow (CVE-2026-62381) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-62381

luci-lib-px5g 2040-bit Certificate Signing Heap Buffer Overflow

Answer in brief

CVE-2026-62381 records a Unknown severity vulnerability in luci-lib-px5g 2040-bit Certificate Signing Heap Buffer Overflow. The current sources do not mark it as known exploited. The current feed maps openwrt/luci (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 22, 2026Updated Aug 22, 2026Source checked Aug 22, 2026First seen by HOL Aug 22, 2026Material review Aug 22, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps openwrt/luci (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
openwrt/lucigeneric	0	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for openwrt/luci.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Aug 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 22, 2026

Sources and claim methodology

Upstream source description

luci-lib-px5g (LuCI) contains a heap-based buffer overflow in the native ASN.1 encoding routine asn1_add_obj (x509write.c) when signing a certificate with a 2040-bit RSA key. For a 255-byte signature, the BIT STRING allocation is computed from the DER length encoding of 255 bytes, but the payload written after prepending the unused-bits byte is 256 bytes, requiring one additional DER length octet. As a result the allocation is 259 bytes while the tag, length, unused-bits byte, and signature require 260 bytes, and the final memcpy writes one byte beyond the heap buffer. The overflow is reachable through the exported Lua interface via create_selfsigned(); whether it is remotely exploitable depends on the embedding application. 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.

Quoted source text, attributed separately from HOL analysis.