DEBIAN-CVE-2026-53994

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Source
https://security-tracker.debian.org/tracker/CVE-2026-53994
Import Source
https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-53994.json
JSON Data
https://api.osv.dev/v1/vulns/DEBIAN-CVE-2026-53994
Upstream
Published
2026-07-18T20:17:30Z
Modified
2026-09-14T17:03:19Z
Severity
  • 6.5 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
Summary
[none]
Details

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.

References

Affected packages

Debian:12 / proftpd-dfsg

Package

Name
proftpd-dfsg
Purl
pkg:deb/debian/proftpd-dfsg?arch=source&distro=bookworm

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.3.8+dfsg-4
1.3.8+dfsg-4+deb12u1
1.3.8+dfsg-4+deb12u2
1.3.8+dfsg-4+deb12u3
1.3.8+dfsg-4+deb12u4
1.3.8+dfsg-4+deb12u5
1.3.8+dfsg-5
1.3.8+dfsg-6
1.3.8+dfsg-7
1.3.8+dfsg-8
1.3.8.a+dfsg-1
1.3.8.b+dfsg-1
1.3.8.b+dfsg-2
1.3.8.b+dfsg-3
1.3.8.b+dfsg-4
1.3.8.c+dfsg-1
1.3.8.c+dfsg-2
1.3.8.c+dfsg-3
1.3.8.c+dfsg-4
1.3.9~dfsg-1
1.3.9~dfsg-2
1.3.9~dfsg-3
1.3.9~dfsg-4
1.3.9~dfsg-5
1.3.9a~dfsg-1
1.3.9b~dfsg-1
1.3.9c~dfsg-1
1.3.9d~dfsg-1

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-53994.json"

Debian:13 / proftpd-dfsg

Package

Name
proftpd-dfsg
Purl
pkg:deb/debian/proftpd-dfsg?arch=source&distro=trixie

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
1.3.8.c+dfsg-4+deb13u3

Affected versions

1.*
1.3.8.c+dfsg-4
1.3.8.c+dfsg-4+deb13u1
1.3.8.c+dfsg-4+deb13u2

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-53994.json"

Debian:14 / proftpd-dfsg

Package

Name
proftpd-dfsg
Purl
pkg:deb/debian/proftpd-dfsg?arch=source&distro=forky

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
1.3.9b~dfsg-1

Affected versions

1.*
1.3.8.c+dfsg-4
1.3.9~dfsg-1
1.3.9~dfsg-2
1.3.9~dfsg-3
1.3.9~dfsg-4
1.3.9~dfsg-5
1.3.9a~dfsg-1

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-53994.json"