# CVE-2026-11850: Krb5: krb5: integer underflow in berval2tl_data() leads to heap out-of-bounds read > An integer underflow in MIT Kerberos allows heap out-of-bounds reads via malicious LDAP data, potentially causing information disclosure or crashes. - **Severity:** Medium 5.0 (`CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** An administrator - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 11 Jun 2026 - **Updated:** 31 Aug 2026 - **Also known as:** BELL-CVE-2026-11850, DEBIAN-CVE-2026-11850, ECHO-b5cb-5a81-96de, GHSA-85rq-mqr4-hjw7, RHSA-2026:25520, ROOT-OS-DEBIAN-12-CVE-2026-11850, ROOT-OS-DEBIAN-13-CVE-2026-11850, SUSE-SU-2026:22450-1, SUSE-SU-2026:22702-1, SUSE-SU-2026:2847-1, SUSE-SU-2026:2849-1, SUSE-SU-2026:2954-1, UBUNTU-CVE-2026-11850, openSUSE-SU-2026:11177-1, openSUSE-SU-2026:21238-1 ## What is CVE-2026-11850? CVE-2026-11850 is a medium-severity vulnerability in Red Hat Enterprise Linux 10, published on 11 Jun 2026. An attacker needs administrator access to exploit it, with no action from the victim. ### Official description An integer underflow vulnerability was found in MIT krb5 in the berval2tl_data() function in plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c. The function performs an unsigned subtraction (bv_len - 2) without a prior bounds check. When bv_len is 0 or 1, the subtraction wraps to a large value which is then truncated to uint16_t, yielding 0xFFFE (65534) or 0xFFFF (65535). The subsequent malloc succeeds and memcpy reads up to 65534 bytes from a 0-1 byte buffer, resulting in a heap out-of-bounds read. The attack vector involves a malicious or compromised LDAP KDB backend returning a krbExtraData attribute with bv_len < 2, triggering the underflow when the KDC or kadmind reads principal data. Weakness: CWE-191 (Integer Underflow (Wrap or Wraparound)) ## Which versions are affected by CVE-2026-11850? | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `krb5` | Red Hat:hummingbird:1 | All versions | 0:1.22.2-8.hum1 | | `krb5-devel` | Red Hat:hummingbird:1 | All versions | 0:1.22.2-8.hum1 | | `krb5-libs` | Red Hat:hummingbird:1 | All versions | 0:1.22.2-8.hum1 | | `krb5-pkinit` | Red Hat:hummingbird:1 | All versions | 0:1.22.2-8.hum1 | | `krb5-server` | Red Hat:hummingbird:1 | All versions | 0:1.22.2-8.hum1 | | `krb5-server-ldap` | Red Hat:hummingbird:1 | All versions | 0:1.22.2-8.hum1 | | `krb5-tests` | Red Hat:hummingbird:1 | All versions | 0:1.22.2-8.hum1 | | `krb5-workstation` | Red Hat:hummingbird:1 | All versions | 0:1.22.2-8.hum1 | | `krb5-xrealmauthz` | Red Hat:hummingbird:1 | All versions | 0:1.22.2-8.hum1 | | `libkadm5` | Red Hat:hummingbird:1 | All versions | 0:1.22.2-8.hum1 | | `krb5` | SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | All versions | 1.19.2-150400.3.24.1 | | `krb5` | SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | All versions | 1.19.2-150400.3.24.1 | | `krb5` | SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | All versions | 1.20.1-150500.3.23.1 | | `krb5` | SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS | All versions | 1.20.1-150500.3.23.1 | | `krb5` | SUSE:Linux Enterprise Micro 5.3 | All versions | 1.19.2-150400.3.24.1 | | `krb5` | SUSE:Linux Enterprise Micro 5.4 | All versions | 1.19.2-150400.3.24.1 | | `krb5` | SUSE:Linux Enterprise Micro 5.5 | All versions | 1.20.1-150500.3.23.1 | | `krb5` | SUSE:Linux Enterprise Server 12 SP5-LTSS | All versions | 1.16.3-46.24.1 | | `krb5` | SUSE:Linux Enterprise Server 15 SP4-LTSS | All versions | 1.19.2-150400.3.24.1 | | `krb5` | SUSE:Linux Enterprise Server 15 SP5-LTSS | All versions | 1.20.1-150500.3.23.1 | | `krb5` | SUSE:Linux Enterprise Server LTSS Extended Security 12 SP5 | All versions | 1.16.3-46.24.1 | | `krb5` | SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | All versions | 1.19.2-150400.3.24.1 | | `krb5` | SUSE:Linux Enterprise Server for SAP Applications 15 SP5 | All versions | 1.20.1-150500.3.23.1 | | `krb5` | SUSE:Linux Micro 6.0 | All versions | 1.20.1-9.1 | | `krb5` | SUSE:Linux Micro 6.1 | All versions | 1.21.3-slfo.1.1_5.1 | | `krb5` | openSUSE:Leap 16.0 | All versions | 1.21.3-160000.4.1 | | `krb5` | openSUSE:Tumbleweed | All versions | 1.22.2-4.1 | ## How do I fix CVE-2026-11850? Apply the vendor's patch. ## Is CVE-2026-11850 being exploited? There is no known exploitation of CVE-2026-11850 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-11850 and fix it if it is affected. What it is: CVE-2026-11850 is a medium-severity vulnerability in Red Hat Enterprise Linux 10, published on 11 Jun 2026. An attacker needs administrator access to exploit it, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-11850 in the wild and no public exploit code. Affected product: Red Hat Enterprise Linux 10. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-11850/ (Markdown: https://insights.sbomify.com/CVE-2026-11850/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-11850 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-11850 - OSV: https://osv.dev/vulnerability/CVE-2026-11850 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-11850/ Summaries are generated and may contain mistakes; the official description above is the record.