A TFTP server that answers with a short ERROR packet makes the client read up to 64 bytes past...
Summary
Vulnerability reported (CVE-2026-102721). Risk of unauthorized operations or information disclosure. Exploitable via buffer_ptr.
Original description
The description as published by the source.
A TFTP server that answers with a short ERROR packet makes the client read up to 64 bytes past the
received datagram.
Each receive path checks only that the datagram is at least four bytes long (nxd_tftp_client.c:1229,
1521, 1984). When the opcode is NX_TFTP_CODE_ERROR the message string is copied with a loop whose
only limits are the destination buffer and a NUL byte:
/* addons/tftp/nxd_tftp_client.c:1769 */
for (i = 0; (i < (sizeof(tftp_client_ptr -> nx_tftp_client_error_string) - 1)) && (*buffer_ptr); i++)
Nothing compares buffer_ptr against nx_packet_append_ptr. An ERROR packet that carries no
terminating NUL, which a server controls completely, walks the loop off the end of the packet until
it happens to meet a zero byte or fills the 64 byte destination.
ERROR: AddressSanitizer: heap-buffer-overflow
READ of size 1 at 0x60d0000000c8 thread T4
#0 _nxd_tftp_client_file_read addons/tftp/nxd_tftp_client.c:1769
0x60d0000000c8 is 0 bytes to the right of 136-byte region
The open path has the same loop at :1327 and reports the same way. What is read lands in
nx_tftp_client_error_string, which the application is expected to display or log, so adjacent
packet pool memory ends up in whatever the device does with the error text.
Add (buffer_ptr < packet_ptr -> nx_packet_append_ptr) to the loop condition in all three paths.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-102721 has been found.
Attackers can target a specific entry point like buffer_ptr over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "CVE-2026-102721" on the vendor's site.
CVE-2026-102721 — CWE-125
Attack surface: buffer_ptr / nx_packet_append_ptr / nx_tftp_client_error_string
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Out-of-bounds read (CWE-125) has been reported. Attackers reach the vulnerable code path via buffer_ptr.
Check the vendor advisory for the affected versions. Attack surface: buffer_ptr / nx_packet_append_ptr / nx_tftp_client_error_string.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで影響コンポーネントを特定する。
-
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
References
- web github.com
- web nvd.nist.gov
- web github.com