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CVE-2026-72378
afs: Fix error code in afs_extract_vl_addrs()
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem fs/afs. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-72378 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 | fixed | 6.1.180-1 | Update the kernel and reboot. Fixed in 6.1.180-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.100-1 | Update the kernel and reboot. Fixed in 6.12.100-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The error codes on these paths are only set on the first iteration through the loop. Set the correct error code on every iteration.
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.
fs/afs/vl_list.c
- What this is
- AFS FILESYSTEMMAINTAINERS section matched on fs/afs/ · linux-afs@lists.infradead.org · Supported
- Kernel module
- kafs
Check it on the machine
grep -w CONFIG_AFS_FS /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 kafsPrints 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, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookworm, trixie, forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- M
- a module where it is built at all; some flavours do not build it
- Build switch
- CONFIG_AFS_FS
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
- 2026-08-15 (2 months ago)source
- CVSS
- 7.5 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.72%, higher than 52.9% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- fs/afs
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.20 | 5.10.261 | 7ce6737a975e |
| 4.20 | 5.15.212 | 4e0b047848a8 |
| 4.20 | 6.1.178 | f70fbf2b974b |
| 4.20 | 6.6.145 | 9ad9016e3333 |
| 4.20 | 6.12.97 | cb33dd296858 |
| 4.20 | 6.18.40 | 8530206911fd |
| 4.20 | 7.1.5 | bdcd80ff1293 |
| 4.20 | 7.2 | 4897cb71d4ab |
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
- Malformed data reaches afs_extract_vl_addrs() from DNS AFSDB server-list replies fetched over the network via dns_query()/request_key upcall during afs_dns_query() cell VL lookups and periodic TTL refresh.
- AC:LAttack complexity, low
- An attacker who can supply the DNS server-list payload can reliably trigger the bug by encoding two or more addresses with a valid first entry and a truncated second IPv4/IPv6 record, forcing the stale ret=0 error path on iteration two or later.
- PR:NPrivileges required, none
- No local account or kernel capabilities are required on the victim; a network-positioned attacker can deliver the malicious binary DNS server-list response whenever the kAFS client resolves an AFSDB record for a targeted cell name.
- UI:NUser interaction, none
- Exploitation does not require victim interaction at trigger time because kAFS automatically re-queries DNS on cell setup and TTL expiry through afs_update_cell(), so a poisoned response can crash the kernel without further user action.
- S:UScope, unchanged
- The flaw is a kernel NULL-pointer dereference in AFS DNS parsing that crashes the local host; it does not cross a VM, container, or IOMMU security boundary to affect a different authority.
- C:NConfidentiality impact, none
- The failure mode is returning ERR_PTR(0) after freeing the address list, causing a NULL dereference in the caller; there is no out-of-bounds read, use-after-free reuse, or other memory disclosure primitive.
- I:NIntegrity impact, none
- Impact is limited to a kernel oops from writing addrs->source on a NULL pointer after a parse error is mishandled; no attacker-controlled memory corruption or arbitrary write primitive is established.
- A:HAvailability impact, high
- The NULL pointer dereference in afs_extract_vlserver_list() runs in the kAFS cell manager workqueue during DNS parsing and causes a kernel oops or panic, fully denying system availability.