# CVE-2026-8674: Assertion failure in the DNS stub resolver with a long search domain > A local network attacker can cause a denial of service in applications using the GNU C Library by providing a long DNS search domain via DHCP or VPN configuration. - **Severity:** Medium 5.3 (`CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 17 Sep 2026 - **Updated:** 17 Sep 2026 - **Also known as:** AZL-101843, BELL-CVE-2026-8674, DEBIAN-CVE-2026-8674, ECHO-00de-f7d3-2e21, GHSA-qghr-qhfc-4hxp, OESA-2026-4016, RHSA-2026:69276, UBUNTU-CVE-2026-8674 ## What is CVE-2026-8674? CVE-2026-8674 is a medium-severity denial of service vulnerability in The GNU C Library glibc, published on 17 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description Initializing the DNS stub resolver from an /etc/resolv.conf file, or a LOCALDOMAIN environment variable, whose search list contains a domain of roughly 200 characters or more in the GNU C Library version 2.26 to 2.44 results in an assertion failure which aborts the process. The resolver truncates the search list when copying it into the fixed-size _res.defdname buffer, then asserts that the copy is consistent with the full configuration. The consistency check compared against the wrong size and did not handle a first entry that does not fit, so a correctly truncated list failed the assertion. Any process that resolves names through the library is affected, including long-running processes that reload /etc/resolv.conf on the next query after it changes. Search domains are commonly written to /etc/resolv.conf from data received over DHCP or from a VPN server, so an attacker on the local network may be able to trigger this without privileges on the target system, subject to validation by the network configuration software. Weakness: CWE-617 (Reachable Assertion) ## Which versions are affected by CVE-2026-8674? | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `compat-libpthread-nonshared` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-all-langpacks` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-benchtests` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-common` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-devel` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-doc` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-gconv-extra` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-aa` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-af` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-agr` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-ak` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-am` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-an` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-anp` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-ar` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-as` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-ast` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-ayc` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-az` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-be` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-bem` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-ber` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-bg` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-bhb` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-bho` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-bi` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-bn` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-bo` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-br` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-brx` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-bs` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-byn` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-ca` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-ce` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-chr` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-ckb` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-cmn` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-crh` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | | `glibc-langpack-cs` | Red Hat:hummingbird:1 | All versions | 0:2.43-8.6.hum1 | ## How do I fix CVE-2026-8674? Apply the vendor's patch. ## Is CVE-2026-8674 being exploited? There is no known exploitation of CVE-2026-8674 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-8674 and fix it if it is affected. What it is: CVE-2026-8674 is a medium-severity denial of service vulnerability in The GNU C Library glibc, published on 17 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-8674 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-2026-8674/ (Markdown: https://insights.sbomify.com/CVE-2026-8674/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-8674 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-8674 - OSV: https://osv.dev/vulnerability/CVE-2026-8674 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-8674/ Summaries are generated and may contain mistakes; the official description above is the record.