CVE-2017-15118
Description
A stack-based buffer overflow vulnerability was found in NBD server implementation in qemu before 2.11 allowing a client to request an export name of size up to 4096 bytes, which in fact should be limited to 256 bytes, causing an out-of-bounds stack write in the qemu process. If NBD server requires TLS, the attacker cannot trigger the buffer overflow without first successfully negotiating TLS.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
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Exploits
Public proof-of-concept code below. AS-IS, for defenders and authorised testing only.
Exploit-DB
QEMU - NBD Server Long Export Name Stack Buffer Overflow
Introduced in commit f37708f6b8 (2.10). The NBD spec says a client
can request export names up to 4096 bytes in length, even though
they should not expect success on names longer than 256. However,
qemu hard-codes the limit of 256, and fails to filter out a client
that probes for a longer name; the result is a stack smash that can
potentially give an attacker arbitrary control over the qemu
process.
The smash can be easily demonstrated with this client:
$ qemu-io f raw nbd://localhost:10809/$(printf %3000d 1 | tr ' ' a)
If the qemu NBD server binary (whether the standalone qemu-nbd, or
the builtin server of QMP nbd-server-start) was compiled with
-fstack-protector-strong, the ability to exploit the stack smash
into arbitrary execution is a lot more difficult (but still
theoretically possible to a determined attacker, perhaps in
combination with other CVEs). Still, crashing a running qemu (and
losing the VM) is bad enough, even if the attacker did not obtain
full execution control.OS impact
Debian Fixed 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Fixed | 1:2.11+dfsg-1 |
| sid | Fixed | 1:2.11+dfsg-1 |
| forky | Fixed | 1:2.11+dfsg-1 |
| bullseye | Fixed | 1:2.11+dfsg-1 |
| bookworm | Fixed | 1:2.11+dfsg-1 |
References
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.