Unauthenticated Arbitrary File Read via Null Byte Injection

published 2025-11-26 11 mo ago modified 2026-10-19 20 d ago also EUVD-2025-199670

cvss: 7.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 36%
public exploits: 0; none known

Unauthenticated Arbitrary File Read via Null Byte Injection in DB Electronica Telecomunicazioni S.p.A. Mozart FM Transmitter versions 30, 50, 100, 300, 500, 1000, 2000, 3000, 3500, 6000, 7000 allows an attacker to perform Null byte injection in download_setting.php allows reading arbitrary files. The `/var/tdf/download_setting.php` endpoint constructs file paths by concatenating user-controlled `$_GET['filename']` with a forced `.tgz` extension. Running on PHP 5.3.2 (pre-5.3.4), the application is vulnerable to null byte injection (%00), allowing attackers to bypass the extension restriction and traverse paths. By requesting `filename=../../../../etc/passwd%00`, the underlying C functions treat the null byte as a string terminator, ignoring the appended `.tgz` and enabling unauthenticated arbitrary file disclosure of any file readable by the web server user.

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 11 mo ago (2025-11-26)

Exploit prediction

0.42% chance of exploitation in the next 30 days, higher than 36% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

abdulmhsblog.com https://www.abdulmhsblog.com/posts/webfmvulns/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	8.9	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N
CNA	4.0	8.9	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

DB Electronica Telecomunicazioni S.p.A. Mozart FM Transmitter

Classification

Weakness

CWE-158 Improper Neutralization of Null Byte or NUL Character

References

abdulmhsblog.com /posts/webfmvulns/
exploit, technical-description, third-party-advisory

Sources

CVE List CVE-2025-66263
NVD CVE-2025-66263

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary