Description
OpenLDAP Lightning Memory-Mapped Database (LMDB) versions 0.9.14 before 0.9.34, prior to commit 8e1fda8, contain a heap buffer underflow in the readline() function of mdb_load. When processing malformed input containing an embedded NUL byte, an unsigned offset calculation can underflow and cause an out-of-bounds read of one byte before the allocated heap buffer. This can cause mdb_load to crash, leading to a limited denial-of-service condition.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| OpenLDAP Foundation | OpenLDAP | 0.9.14 – < 0.9.34 | 0.9.34 |
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 | lmdb | 0.9.35-1 | — |
| Debian 14 | openldap | No fix yet | — |
| Debian 13 | lmdb +1 | No fix yet | — |
| Debian 12 | lmdb +1 | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | lmdb | No fix yet | — |
| Ubuntu 26.04 LTS | lmdb | No fix yet | — |
| Ubuntu 25.10 | lmdb | No fix yet | — |
| Ubuntu 24.04 LTS | lmdb | No fix yet | — |
| Ubuntu 22.04 LTS | lmdb | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | lmdb | No fix yet | — |
| Ubuntu 18.04 LTS | lmdb | No fix yet | — |
| Ubuntu 16.04 LTS | lmdb | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | openldap2_5 | 2.5.20+11-150500.11.38.1 | SUSE-SU-2026:0256-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 15.6 | openldap2_5 | 2.5.20+11-150500.11.38.1 | SUSE-SU-2026:0256-1 |
Advisories 2
- SUSE-SU-2026:0256-1 Security update for openldap2_5 SUSE / openSUSE Security Updates · Mar 23, 2026
- WID-SEC-2026-0036 OpenLDAP: Schwachstelle ermöglicht Denial of Service und Offenlegung von Informationen BSI CERT-Bund (WID) · Jan 22, 2026
References
- https://seclists.org/fulldisclosure/2026/Jan/5 technical-description exploit
- https://seclists.org/fulldisclosure/2026/Jan/8 technical-description exploit
- https://www.openldap.org/ product
- https://www.vulncheck.com/advisories/openldap-lmdb-mdb-load-heap-buffer-underflow-in-readline third-party-advisory
- https://bugs.openldap.org/show_bug.cgi?id=10421 issue-tracking patch