Description
The recv_msg_userauth_request function in svr-auth.c in Dropbear through 2018.76 is prone to a user enumeration vulnerability because username validity affects how fields in SSH_MSG_USERAUTH messages are handled, a similar issue to CVE-2018-15473 in an unrelated codebase.
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 | dropbear | 2018.76-4 | — |
| Debian 13 | dropbear | 2018.76-4 | — |
| Debian 12 | dropbear | 2018.76-4 | — |
| Debian 8 | dropbear | 2014.65-1+deb8u3 | DLA-1476-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | dropbear | No fix yet | — |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 18.04 LTS | dropbear | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | signing-party | 2.11-1.3 | openSUSE-SU-2024:11383-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | dropbear | 2018.76-r2 | — |
| Alpine v3.23 | dropbear | 2018.76-r2 | — |
| Alpine v3.22 | dropbear | 2018.76-r2 | — |
| Alpine v3.21 | dropbear | 2018.76-r2 | — |
| Alpine v3.20 | dropbear | 2018.76-r2 | — |
Show 15 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | dropbear | 2018.76-r2 | — |
| Alpine v3.18 | dropbear | 2018.76-r2 | — |
| Alpine v3.17 | dropbear | 2018.76-r2 | — |
| Alpine v3.16 | dropbear | 2018.76-r2 | — |
| Alpine v3.15 | dropbear | 2018.76-r2 | — |
| Alpine v3.14 | dropbear | 2018.76-r2 | — |
| Alpine v3.13 | dropbear | 2018.76-r2 | — |
| Alpine v3.12 | dropbear | 2018.76-r2 | — |
| Alpine v3.11 | dropbear | 2018.76-r2 | — |
| Alpine v3.10 | dropbear | 2018.76-r2 | — |
| Alpine v3.9 | dropbear | 2018.76-r2 | — |
| Alpine v3.8 | dropbear | 2018.76-r2 | — |
| Alpine v3.7 | dropbear | 2018.76-r2 | — |
| Alpine v3.6 | dropbear | 2017.75-r1 | — |
| Alpine v3.5 | dropbear | 2017.75-r1 | — |
Advisories 2
- DLA-1476-1 dropbear - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:11383-1 signing-party-2.11-1.3 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
References
- https://matt.ucc.asn.au/dropbear/CHANGES
- http://lists.ucc.gu.uwa.edu.au/pipermail/dropbear/2018q3/002109.html
- http://lists.ucc.gu.uwa.edu.au/pipermail/dropbear/2018q3/002108.html
- [debian-lts-announce] 20180827 [SECURITY] [DLA 1476-1] dropbear security update mailing-list
- https://old.reddit.com/r/blackhat/comments/97ywnm/openssh_username_enumeration/e4e05n2/