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CVE-2026-53002
netfilter: conntrack: remove sprintf usage
Published 2026-06-24 (4 months ago) by the Linux kernel CNA. Subsystem net/netfilter. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-53002 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixedDLA-4665-1 · 2026-07-03 · text | 6.1.176-1 | Update the kernel and reboot. DLA-4665-1 shipped the fix on 2026-07-03, in 6.1.176-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Replace it with scnprintf, the buffer sizes are expected to be large enough to hold the result, no need for snprintf+overflow check. Increase buffer size in mangle_content_len() while at it. BUG: KASAN: stack-out-of-bounds in vsnprintf+0xea5/0x1270 Write of size 1 at addr [..] vsnprintf+0xea5/0x1270 sprintf+0xb1/0xe0 mangle_content_len+0x1ac/0x280 nf_nat_sdp_session+0x1cc/0x240 process_sdp+0x8f8/0xb80 process_invite_request+0x108/0x2b0 process_sip_msg+0x5da/0xf50 sip_help_tcp+0x45e/0x780 nf_confirm+0x34d/0x990 [..]
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
net/netfilter/nf_nat_amanda.c
net/netfilter/nf_nat_sip.c
- What this is
- NETFILTERMAINTAINERS section matched on net/netfilter/ · netfilter-devel@vger.kernel.org · Maintained
- Kernel module
- nf_nat_amanda
Check it on the machine
grep -wE 'CONFIG_NETFILTER|CONFIG_NF_NAT_AMANDA' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w nf_nat_amandaPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this as a loadable module. Every release below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded.
- bookworm, trixie, forky, sidm
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switches
- CONFIG_NETFILTER, CONFIG_NF_NAT_AMANDA
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-06-24 (4 months ago)source
- CVSS
- 9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.37%, higher than 29.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/netfilter
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.20 | 5.10.258 | 2f793ba78470 |
| 2.6.20 | 5.15.209 | 6bbf829b4c1b |
| 2.6.20 | 6.1.175 | ab64e61c9323 |
| 2.6.20 | 6.6.141 | 1c9fb8aeed06 |
| 2.6.20 | 6.12.91 | a8e0a32a23d3 |
| 2.6.20 | 6.18.33 | 8e3be0d12615 |
| 2.6.20 | 7.0.10 | c08ff52e4494 |
| 2.6.20 | 7.1 | 6e7066bdb481 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4671-1 | 2026-07-05 | bullseye 6.1.176-1~deb11u1 | tracker |
| DLA-4665-1 | 2026-07-03 | bookworm 6.1.176-1 | tracker |
| DLA-4664-1 | 2026-07-03 | bullseye 5.10.259-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:NAttack vector, network
- The vulnerable SIP NAT helper is reached from network packet processing when a target acts as a SIP-aware NAT/conntrack gateway. A remote peer can send crafted SIP/SDP traffic through that configured path.
- AC:LAttack complexity, low
- No race or hard-to-control state is required; the attacker controls the SIP/SDP payload and can drive the oversized Content-Length recomputation. The needed NAT/helper configuration is a normal deployment condition for SIP ALG/firewall use.
- PR:NPrivileges required, none
- In the remote deployment scenario, the attacker only sends network traffic and does not need local credentials or administrative privileges on the target. Local helper setup would require CAP_NET_ADMIN, but that is not required when attacking an already configured SIP NAT gateway.
- UI:NUser interaction, none
- No victim user action is required once the vulnerable helper is active. Packet processing happens automatically in the netfilter conntrack/NAT path.
- S:UScope, unchanged
- The corruption occurs inside the Linux kernel networking stack and impacts the same kernel security authority. There is no VM, IOMMU, or cross-authority boundary change.
- C:HConfidentiality impact, high
- This is kernel stack memory corruption from an out-of-bounds sprintf write. Even though the report shows a KASAN crash, such memory corruption can plausibly be leveraged toward broader kernel compromise, so the higher severity value is appropriate.
- I:HIntegrity impact, high
- The bug is an out-of-bounds write on the kernel stack in packet processing. Kernel memory corruption can plausibly alter control data or enable code execution, so integrity impact is high.
- A:HAvailability impact, high
- The reported failure is a KASAN stack-out-of-bounds write in kernel context and can crash or panic the system. The crafted traffic can be sent repeatedly to sustain denial of service.