Description
A heap-based buffer overflow flaw was found in Cyrus SASL. The add_to_challenge() function in the DIGEST-MD5 plugin computes the size of the buffer needed for a challenge/response field before DIGEST-MD5 quoting is applied, but does not recompute that size when quoting (escaping special characters) makes the value longer. The under-sized buffer is then passed to strcat(), causing a heap-based out-of-bounds write whose size depends on attacker-controlled input. A malicious or on-path DIGEST-MD5 (or HTTP Digest) server can trigger this flaw in a connecting client by supplying a crafted challenge field, such as realm or nonce, most likely resulting in a crash of the client application.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 | — | — |
| Red Hat | Red Hat Enterprise Linux 6 | — | — |
| Red Hat | Red Hat Enterprise Linux 7 | — | — |
| Red Hat | Red Hat Enterprise Linux 8 | — | — |
| Red Hat | Red Hat Enterprise Linux 9 | — | — |
| Red Hat | Red Hat Hardened Images | — | — |
| Red Hat | Red Hat OpenShift AI (RHOAI) | — | — |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — |
| Red Hat | Red Hat OpenShift Container Platform 5 | — | — |
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 | cyrus-sasl2 | 2.1.28+dfsg1-12 | — |
| Debian 13 | cyrus-sasl2 | No fix yet | — |
| Debian 12 | cyrus-sasl2 | 2.1.28+dfsg-10+deb12u1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | cyrus-sasl2 | No fix yet | — |
| Ubuntu 26.04 LTS | cyrus-sasl2 | No fix yet | — |
| Ubuntu 24.04 LTS | cyrus-sasl2 | No fix yet | — |
| Ubuntu 22.04 LTS | cyrus-sasl2 | No fix yet | — |
| Ubuntu 20.04 LTS | cyrus-sasl2 | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | cyrus-sasl2 | No fix yet | — |
| Ubuntu Pro 16.04 LTS | cyrus-sasl2 | No fix yet | — |
| Ubuntu Pro 14.04 LTS | cyrus-sasl2 | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | cyrus-sasl +3 | 2.1.28-150600.7.17.1 | SUSE-SU-2026:4836-1 |
| SLES 15 SP6 | cyrus-sasl +3 | 2.1.28-150600.7.17.1 | SUSE-SU-2026:4836-1 |
| SLES 15 SP5 | cyrus-sasl +3 | 2.1.28-150500.3.12.1 | SUSE-SU-2026:4817-1 |
| SLES 15 SP4 | cyrus-sasl +3 | 2.1.27-150300.4.9.1 | SUSE-SU-2026:4802-1 |
| SLES 12 SP5 | cyrus-sasl +1 | 2.1.26-14.10.1 | SUSE-SU-2026:4795-1 |
Show 12 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | cyrus-sasl +1 | 2.1.28-160000.4.1 | SUSE-SU-2026:24266-1 |
| SLES for SAP 15 SP6 | cyrus-sasl +3 | 2.1.28-150600.7.17.1 | SUSE-SU-2026:4836-1 |
| SLES for SAP 15 SP5 | cyrus-sasl +3 | 2.1.28-150500.3.12.1 | SUSE-SU-2026:4817-1 |
| SLES for SAP 15 SP4 | cyrus-sasl +3 | 2.1.27-150300.4.9.1 | SUSE-SU-2026:4802-1 |
| SLES 16.0 | cyrus-sasl +1 | 2.1.28-160000.4.1 | SUSE-SU-2026:24266-1 |
| SLE Micro 6.2 | cyrus-sasl | 2.1.28-160000.4.1 | SUSE-SU-2026:24405-1 |
| SLE Micro 6.1 | cyrus-sasl | 2.1.28-slfo.1.1_2.1 | SUSE-SU-2026:24380-1 |
| SLE Micro 5.5 | cyrus-sasl | 2.1.28-150500.3.12.1 | SUSE-SU-2026:4817-1 |
| SLE Micro 5.4 | cyrus-sasl | 2.1.27-150300.4.9.1 | SUSE-SU-2026:4802-1 |
| SLE Micro 5.3 | cyrus-sasl | 2.1.27-150300.4.9.1 | SUSE-SU-2026:4802-1 |
| SLE HPC 15 SP5 | cyrus-sasl +2 | 2.1.28-150500.3.12.1 | SUSE-SU-2026:4817-1 |
| SLE HPC 15 SP4 | cyrus-sasl +3 | 2.1.27-150300.4.9.1 | SUSE-SU-2026:4802-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | cyrus-sasl | 2.1.28-13.1 | openSUSE-SU-2026:12099-1 |
| openSUSE Leap 16.0 | cyrus-sasl +3 | 2.1.28-160000.4.1 | openSUSE-SU-2026:22146-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | cyrus-sasl +10 | 2.1.27-18.amzn2023.0.4 | ALAS2023-2026-3290 |
| Amazon Linux 2 | cyrus-sasl +10 | 2.1.26-24.amzn2.0.2 | ALAS2-2026-4029 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | cyrus-sasl +1 | No fix yet | — |
Advisories 11
- SUSE-SU-2026:24405-1 Security update for cyrus-sasl SUSE / openSUSE Security Updates · Oct 30, 2026
- SUSE-SU-2026:24380-1 Security update for cyrus-sasl SUSE / openSUSE Security Updates · Oct 27, 2026
- ALAS2023-2026-3290 Important: cyrus-sasl security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Oct 26, 2026
- ALAS2-2026-4029 Important: cyrus-sasl security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Oct 26, 2026
- openSUSE-SU-2026:22146-1 Security update for cyrus-sasl SUSE / openSUSE Security Updates · Oct 23, 2026
- SUSE-SU-2026:24266-1 Security update for cyrus-sasl SUSE / openSUSE Security Updates · Oct 23, 2026
- SUSE-SU-2026:4836-1 Security update for cyrus-sasl SUSE / openSUSE Security Updates · Oct 22, 2026
- SUSE-SU-2026:4802-1 Security update for cyrus-sasl SUSE / openSUSE Security Updates · Oct 21, 2026
- SUSE-SU-2026:4795-1 Security update for cyrus-sasl SUSE / openSUSE Security Updates · Oct 21, 2026
- SUSE-SU-2026:4817-1 Security update for cyrus-sasl SUSE / openSUSE Security Updates · Oct 21, 2026
- openSUSE-SU-2026:12099-1 cyrus-sasl-2.1.28-13.1 on GA media SUSE / openSUSE Security Updates · Oct 11, 2026
References
- https://access.redhat.com/security/cve/CVE-2026-107161 vdb-entry
- RHBZ#2460420 issue-tracking