Description
Libntlm through 1.5 relies on a fixed buffer size for tSmbNtlmAuthRequest, tSmbNtlmAuthChallenge, and tSmbNtlmAuthResponse read and write operations, as demonstrated by a stack-based buffer over-read in buildSmbNtlmAuthRequest in smbutil.c for a crafted NTLM request.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | libntlm | 1.6-1 | — |
| Debian 13 | libntlm | 1.6-1 | — |
| Debian 12 | libntlm | 1.6-1 | — |
| Debian 9 | libntlm | 1.4-8+deb9u1 | DLA-2831-1 |
| Debian 8 | libntlm | 1.4-3+deb8u1 | DLA-2207-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | libntlm | 1.5-2ubuntu0.1 | USN-5108-1 |
| Ubuntu 18.04 LTS | libntlm | 1.4-8ubuntu0.1 | USN-5108-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 16.04 LTS | libntlm | 1.4-7ubuntu0.1~esm1 | USN-5108-2 |
| Ubuntu Pro 14.04 LTS | libntlm | 1.4-1ubuntu0.1~esm1 | USN-5108-2 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SUSE Package Hub 15 SP1 | libntlm | 1.6-bp151.4.3.1 | openSUSE-SU-2020:0816-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 15.1 | libntlm | 1.6-lp151.3.3.1 | openSUSE-SU-2020:0806-1 |
Advisories 6
- USN-5108-2 libntlm vulnerability Ubuntu Security Notices (USN) · Jun 29, 2026
- USN-5108-1 libntlm vulnerability Ubuntu Security Notices (USN) · Apr 22, 2026
- DLA-2207-1 libntlm - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-2831-1 libntlm - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2020:0816-1 Security update for libntlm SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:0806-1 Security update for libntlm SUSE / openSUSE Security Updates · Feb 4, 2026
References
- https://gitlab.com/jas/libntlm/issues/2
- https://people.canonical.com/~ubuntu-security/cve/2019/CVE-2019-17455.html
- https://security-tracker.debian.org/tracker/CVE-2019-17455
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=942145
- [debian-lts-announce] 20200510 [SECURITY] [DLA 2207-1] libntlm security update mailing-list
- openSUSE-SU-2020:0816 vendor-advisory
- openSUSE-SU-2020:0806 vendor-advisory
- FEDORA-2020-8794383d6f vendor-advisory
- FEDORA-2020-1f643c272c vendor-advisory
- [debian-lts-announce] 20211128 [SECURITY] [DLA 2831-1] libntlm security update mailing-list