# CVE-2026-11979: Stack-Based Buffer Overflow in libxml2 > Stack-based buffer overflow in libxml2's xmlcatalog utility allows arbitrary code execution or crashes when processing long input in shell mode. - **Severity:** Low 1.8 (`CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:L/SC:L/SI:L/SA:N`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Local or same network only - **Victim action needed:** A user has to click or open something - **Fix available:** Yes - **Published:** 29 Jun 2026 - **Updated:** 29 Jun 2026 - **Also known as:** ALSA-2026:60394, ALSA-2026:61248, CLSA-2026-1782998484, CLSA-2026-1783006034, CLSA-2026-1783076182, CLSA-2026-1783076452, CLSA-2026-1783093006, CLSA-2026-1783093248, CLSA-2026-1783095251, CLSA-2026-1783095447, CLSA-2026-1783587336, CLSA-2026-1783587973, CLSA-2026-1783588204, CLSA-2026-1783632090, CLSA-2026-1783670609, CLSA-2026-1783948495, DEBIAN-CVE-2026-11979, ECHO-eb03-65da-1e8c, GHSA-h67q-h62w-5mjr, OESA-2026-3039, RHSA-2026:33840, RHSA-2026:60394, RHSA-2026:61248, RLSA-2026:60394, RLSA-2026:61248, SUSE-SU-2026:22806-1, SUSE-SU-2026:22894-1, SUSE-SU-2026:3095-1, SUSE-SU-2026:3096-1, SUSE-SU-2026:3097-1, SUSE-SU-2026:3111-1, UBUNTU-CVE-2026-11979, openSUSE-SU-2026:11258-1 ## What is CVE-2026-11979? CVE-2026-11979 is a low-severity memory corruption vulnerability in Xmlsoft Libxml2, published on 29 Jun 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link. ### Official description libxml2 is vulnerable to multiple stack-based buffer overflows in the xmlcatalog utility when running in --shell mode. The usershell() function processes user input using fixed-size stack buffers without proper bounds checking. By supplying an overly long input line, an attacker can overflow internal buffers (command, arg, and argv) during input parsing. This results in memory corruption within the stack frame. Successful exploitation may cause a crash or potentially allow arbitrary code execution in the context of the xmlcatalog process. This issue has been fixed in the commit c2e233fc. NOTE: The maintainers of this project did not agree that this issue is a vulnerability and considered it a bug. Weakness: CWE-121 (Stack-based Buffer Overflow) ## Which versions are affected by CVE-2026-11979? It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `libxml2` | AlmaLinux:10 | All versions | 2.12.5-10.el10_2.3 | | `libxml2-devel` | AlmaLinux:10 | All versions | 2.12.5-10.el10_2.3 | | `libxml2-static` | AlmaLinux:10 | All versions | 2.12.5-10.el10_2.3 | | `python3-libxml2` | AlmaLinux:10 | All versions | 2.12.5-10.el10_2.3 | | `libxml2` | AlmaLinux:8 | All versions | 2.9.7-21.el8_10.7 | | `libxml2-devel` | AlmaLinux:8 | All versions | 2.9.7-21.el8_10.7 | | `python3-libxml2` | AlmaLinux:8 | All versions | 2.9.7-21.el8_10.7 | | `libxml2` | Red Hat:enterprise_linux:10.2 | All versions | 0:2.12.5-10.el10_2.3 | | `libxml2-debuginfo` | Red Hat:enterprise_linux:10.2 | All versions | 0:2.12.5-10.el10_2.3 | | `libxml2-debugsource` | Red Hat:enterprise_linux:10.2 | All versions | 0:2.12.5-10.el10_2.3 | | `libxml2-devel` | Red Hat:enterprise_linux:10.2 | All versions | 0:2.12.5-10.el10_2.3 | | `libxml2-static` | Red Hat:enterprise_linux:10.2 | All versions | 0:2.12.5-10.el10_2.3 | | `python3-libxml2` | Red Hat:enterprise_linux:10.2 | All versions | 0:2.12.5-10.el10_2.3 | | `python3-libxml2-debuginfo` | Red Hat:enterprise_linux:10.2 | All versions | 0:2.12.5-10.el10_2.3 | | `libxml2-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.9.7-21.el8_10.7 | | `libxml2-debugsource` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.9.7-21.el8_10.7 | | `libxml2-devel` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.9.7-21.el8_10.7 | | `python3-libxml2-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.9.7-21.el8_10.7 | | `libxml2` | Red Hat:enterprise_linux:8::baseos | All versions | 0:2.9.7-21.el8_10.7 | | `libxml2-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 0:2.9.7-21.el8_10.7 | | `libxml2-debugsource` | Red Hat:enterprise_linux:8::baseos | All versions | 0:2.9.7-21.el8_10.7 | | `python3-libxml2` | Red Hat:enterprise_linux:8::baseos | All versions | 0:2.9.7-21.el8_10.7 | | `python3-libxml2-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 0:2.9.7-21.el8_10.7 | | `libxml2` | Red Hat:hummingbird:1 | All versions | 0:2.15.3-0.1.1.hum1 | | `libxml2-16` | Red Hat:hummingbird:1 | All versions | 0:2.15.3-0.1.1.hum1 | | `libxml2-devel` | Red Hat:hummingbird:1 | All versions | 0:2.15.3-0.1.1.hum1 | | `libxml2-static` | Red Hat:hummingbird:1 | All versions | 0:2.15.3-0.1.1.hum1 | | `python3-libxml2` | Red Hat:hummingbird:1 | All versions | 0:2.15.3-0.1.1.hum1 | | `libxml2` | Rocky Linux:10 | All versions | 0:2.12.5-10.el10_2.3 | | `libxml2` | Rocky Linux:8 | All versions | 0:2.9.7-21.el8_10.7 | | `libxml2` | SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | All versions | 2.9.14-150400.5.58.1 | | `libxml2-python` | SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | All versions | 2.9.14-150400.5.58.1 | | `libxml2` | SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | All versions | 2.9.14-150400.5.58.1 | | `libxml2-python` | SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | All versions | 2.9.14-150400.5.58.1 | | `libxml2` | SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | All versions | 2.10.3-150500.5.41.1 | | `libxml2-python` | SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | All versions | 2.10.3-150500.5.41.1 | | `libxml2` | SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS | All versions | 2.10.3-150500.5.41.1 | | `libxml2-python` | SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS | All versions | 2.10.3-150500.5.41.1 | | `libxml2` | SUSE:Linux Enterprise Micro 5.3 | All versions | 2.9.14-150400.5.58.1 | | `libxml2-python` | SUSE:Linux Enterprise Micro 5.3 | All versions | 2.9.14-150400.5.58.1 | Products: Xmlsoft Libxml2. ## How do I fix CVE-2026-11979? Apply the vendor's patch. ## Is CVE-2026-11979 being exploited? There is no known exploitation of CVE-2026-11979 in the wild and no public exploit code. ## Other vulnerabilities in Xmlsoft Libxml2 - [CVE-2017-16931](https://insights.sbomify.com/CVE-2017-16931/): XML external entity in n/a (critical 9.8) - [CVE-2017-8872](https://insights.sbomify.com/CVE-2017-8872/): Information disclosure in n/a (critical 9.1) - [CVE-2022-49043](https://insights.sbomify.com/CVE-2022-49043/): Use after free in libxml2 (high 8.1) - [CVE-2026-86140](https://insights.sbomify.com/CVE-2026-86140/): Memory corruption in libxml2 (high 8.0) - [CVE-2024-34459](https://insights.sbomify.com/CVE-2024-34459/): Memory corruption in n/a (high 7.5) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-11979 and fix it if it is affected. What it is: CVE-2026-11979 is a low-severity memory corruption vulnerability in Xmlsoft Libxml2, published on 29 Jun 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link. Exploitation: There is no known exploitation of CVE-2026-11979 in the wild and no public exploit code. Affected product: Xmlsoft Libxml2. 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-2026-11979/ (Markdown: https://insights.sbomify.com/CVE-2026-11979/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-11979 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-11979 - OSV: https://osv.dev/vulnerability/CVE-2026-11979 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-11979/ Summaries are generated and may contain mistakes; the official description above is the record.