CVE-2026-35025

Published Jun 24, 2026

Last updated 2 months ago

CVSS high 8.6
Port (21)

Overview

AI description

Automated description summarized from trusted sources.

CVE-2026-35025 describes an access control bypass vulnerability found in ProFTPD versions up to and including 1.3.9b and 1.3.10rc2. This flaw enables authenticated FTP users to circumvent Directory Access Control List (ACL) restrictions. The vulnerability is exploited by prefixing paths with `/proc/self/root` within the `RNFR` command handler. This technique allows attackers to leverage unresolved symlink components in `dir_canonical_path()` to cause `dir_check()` to perform lexical path comparisons that bypass configured Directory blocks. Consequently, this permits rename operations on files located in `DenyAll`-protected directories and their subsequent retrieval. It is noted that ProFTPD sessions configured with `DefaultRoot` (chroot) are not susceptible, as chroot modifies the resolution of `/proc/self/root`.

Description
ProFTPD through 1.3.9b and 1.3.10rc2 contains an access control bypass vulnerability that allows authenticated FTP users to circumvent Directory ACL restrictions by prefixing paths with /proc/self/root in the RNFR command handler. Attackers can exploit the unresolved symlink components in dir_canonical_path() to cause dir_check() to perform lexical path comparisons that match no configured Directory block, enabling rename operations on files in DenyAll-protected directories and subsequent retrieval of those files. Mitigation: Sessions configured with DefaultRoot (chroot) are not affected, as chroot changes the directory to which /proc/self/root resolves.
Source
disclosure@vulncheck.com
NVD status
Analyzed
Products
proftpd

Risk scores

CVSS 4.0

Type
Secondary
Base score
8.6
Impact score
-
Exploitability score
-
Vector string
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/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
Severity
HIGH

CVSS 3.1

Type
Secondary
Base score
8.1
Impact score
5.2
Exploitability score
2.8
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Severity
HIGH

Weaknesses

disclosure@vulncheck.com
CWE-59

Social media

Hype score
Not currently trending

  1. CVE-2026-35025: 🚨 CVE-2026-35025: ProFTPD ACL Bypass via /proc/self/root Path Prefix in RNFR Critical Vulnerability Alert! ProFTPD is affected by CVE-2026-35025. Full Vulnerability Details & Analysis at DarkEye: 🔗 🔍 Identify Targets via…

    @lyrie_ai

    20 Jul 2026

    45 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    1 Reply

    0 Quotes

  2. 🚨 CVE-2026-35025: ProFTPD ACL Bypass via /proc/self/root Path Prefix in RNFR Critical Vulnerability Alert! ProFTPD is affected by CVE-2026-35025. Full Vulnerability Details & Analysis at DarkEye: 🔗 https://t.co/gBxlFO3s7H 🔍 Identify Targets via ZoomEye: Filter: h

    @zoomeye_team

    1 Jul 2026

    3194 Impressions

    10 Retweets

    41 Likes

    18 Bookmarks

    1 Reply

    0 Quotes

Configurations

Related CVEs

  1. ProFTPD before 1.3.9c and 1.3.10rc3 contains a signed integer overflow vulnerability in the mod_sftp module's SCP size-record parser that allows authenticated low-privilege attackers to bypass ASLR by sending a crafted file size value of UINT64_MAX, which results in a negative off_t value. Attackers can exploit the subsequent conversion to uint32_t, causing an approximately 4 GB requested read length and forcing the server to read beyond the end of the SSH channel data and write overread process memory into the uploaded file. In tested configurations, the disclosed data contains libc, libcrypto, and PIE pointers sufficient to derive their randomized base addresses, thereby bypassing ASLR and enabling reliable exploitation of memory corruption vulnerabilities in the same process.•CVE-2026-63091
  2. ProFTPD before 1.3.9c and 1.3.10rc3 contains a heap-based buffer overflow vulnerability in the mod_sftp module that allows authenticated low-privilege attackers to achieve arbitrary code execution by sending crafted SFTP packet fragments exceeding the 16 KB reassembly buffer in the fxp.c component. Attackers can supply oversized fragments to trigger an incorrectly conditioned reallocation, corrupt pool freelist metadata, overwrite the root_fs BSS global pointer to reference a fake filesystem struct, and redirect pr_fsio_stat() to system() via a crafted RENAME request.•CVE-2026-63090
  3. ProFTPD mod_sftp contains a heap-based buffer overflow reachable by an authenticated SFTP user. The fxp_packet_read() function accepts the attacker-supplied 32-bit big-endian SFTP packet length without a minimum sanity check. A value of 0 causes an unsigned subtraction elsewhere in the read path to underflow to approximately 4 GB. That oversized request reaches the core memory allocator, where the rounded size is computed in size_t but passed to new_block() as a 32-bit int; the low 32 bits of 0x100000000 are 0, so new_block() returns a small (~512-byte) block while the caller is told it received ~4 GB. The subsequent fill loop then streams attacker-controlled bytes past the end of the 544-byte allocation, producing an attacker-controlled heap buffer overflow. An authenticated user can crash the per-connection ProFTPD session child on demand with a single malformed SFTP packet (packet_len=0 followed by a body greater than approximately 544 bytes), producing reliable authenticated remote denial of service. Depending on heap layout and adjacent allocations, heap metadata corruption and further consequences beyond denial of service may be possible, though only denial of service is demonstrated by the supplied proof of concept.•CVE-2026-53994
  4. Squid is a caching proxy for the Web. Prior to 7.6, due to an improper validation of syntactic correctness of input in the FTP gateway (src/clients/FtpGateway.cc), Squid is vulnerable to an out-of-bounds read: when a listing entry date in the TypeA or TypeB directory-listing formats is not followed by a filename, parsing was not restricted to the input buffer, so a trusted client accessing a misbehaving FTP server through Squid's gateway feature could read memory from random unrelated transactions. This issue is fixed in version 7.6.•CVE-2026-47729
  5. Heap-based buffer overflow in Windows FTP Service allows an unauthorized attacker to execute code over a network.•CVE-2026-49172

References

Sources include official advisories and independent security research.