# CVE-2026-19499: Buffer overflow in strfmon and strfmon_l right-justification padding > Buffer overflow in glibc strfmon functions allows attackers to write past buffer boundaries, potentially causing crashes or code execution. - **Severity:** High 7.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 14 Sep 2026 - **Updated:** 14 Sep 2026 - **Also known as:** AZL-100962, BELL-CVE-2026-19499, DEBIAN-CVE-2026-19499, ECHO-0b68-19f2-1a40, GHSA-3vcj-mghm-mw9p, RHSA-2026:60865, ROOT-OS-DEBIAN-12-CVE-2026-19499, ROOT-OS-DEBIAN-13-CVE-2026-19499, UBUNTU-CVE-2026-19499 ## What is CVE-2026-19499? CVE-2026-19499 is a high-severity memory corruption vulnerability in The GNU C Library glibc, published on 14 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description Calling strfmon and strfmon_l in the GNU C Library version 2.38 to 2.44 can write past the end of the caller-supplied output buffer when a conversion uses right-justified width padding. Exploitation requires an application code path that calls strfmon or strfmon_l with right-justified width padding into a destination buffer that is large enough for the padding to succeed but too small for the internal memmove call. The field width or format may be attacker-influenced or a fixed susceptible pattern in the caller. At the time of publication, no network-facing application impact is known. Weakness: CWE-122 (Heap-based Buffer Overflow) ## Which versions are affected by CVE-2026-19499? | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `compat-libpthread-nonshared` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-all-langpacks` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-benchtests` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-common` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-devel` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-doc` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-gconv-extra` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-aa` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-af` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-agr` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-ak` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-am` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-an` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-anp` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-ar` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-as` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-ast` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-ayc` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-az` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-be` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-bem` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-ber` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-bg` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-bhb` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-bho` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-bi` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-bn` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-bo` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-br` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-brx` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-bs` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-byn` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-ca` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-ce` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-chr` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-ckb` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-cmn` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-crh` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | | `glibc-langpack-cs` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.3.hum1 | ## How do I fix CVE-2026-19499? Apply the vendor's patch. ## Is CVE-2026-19499 being exploited? There is no known exploitation of CVE-2026-19499 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-19499 and fix it if it is affected. What it is: CVE-2026-19499 is a high-severity memory corruption vulnerability in The GNU C Library glibc, published on 14 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-19499 in the wild and no public exploit code. Affected product: The GNU C Library glibc. 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-2026-19499/ (Markdown: https://insights.sbomify.com/CVE-2026-19499/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-19499 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-19499 - OSV: https://osv.dev/vulnerability/CVE-2026-19499 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-19499/ Summaries are generated and may contain mistakes; the official description above is the record.