--- id: CVE-2026-76844 title: >- zlib 1.2.11 through 1.3.2 contains a heap buffer overflow: after an underlying write() fails, gz_write() returns without resetting strm.next_in, leaving it pointed at the caller's buffer summary: >- zlib 1.2.11 through 1.3.2 contains a heap buffer overflow: after an underlying write() fails, gz_write() returns without resetting strm.next_in, leaving it pointed at the caller's buffer. A later gz* write call then derives a position fr… severity: high cvss: 7.4 cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H' cwe: - CWE-787 - CWE-22 vendor: zlib product: zlib affected: - zlib >= 1.2.11 <= 1.3.2 patched: - webpack-dev-middleware 8.3.0 - webpack-dev-middleware 7.4.6 published: '2026-08-24' updated: '2026-10-12' sourceUpdated: '2026-10-12T17:10:00.163' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-76844' references: - url: 'https://gist.github.com/thesmartshadow/e0b9481792afb7c31e86fee1ff084490' label: disclosure@vulncheck.com - url: 'https://github.com/madler/zlib' label: disclosure@vulncheck.com - url: 'https://github.com/madler/zlib/blob/v1.3.2/gzwrite.c#L393' label: disclosure@vulncheck.com - url: >- https://github.com/madler/zlib/commit/df84af25dc1942490e1d1c899a07619152a46148 label: disclosure@vulncheck.com - url: >- https://www.vulncheck.com/advisories/zlib-1.3.1.2-through-1.3.2-heap-buffer-overflow-via-gz-vacate label: disclosure@vulncheck.com - url: 'https://github.com/advisories/GHSA-wr3j-pwj9-hqq6' label: disclosure@vulncheck.com - url: 'https://github.com/webpack/webpack-dev-middleware' label: disclosure@vulncheck.com - url: >- https://github.com/webpack/webpack-dev-middleware/blob/v8.1.1/src/middleware.js label: disclosure@vulncheck.com - url: >- https://github.com/webpack/webpack-dev-middleware/commit/13344e78b26d88fe9b7c8381a3860e248a52359b label: disclosure@vulncheck.com - url: >- https://github.com/webpack/webpack-dev-middleware/commit/cefccbac330c29052fc6dffe85fd292ea2ac782b label: disclosure@vulncheck.com - url: 'https://github.com/webpack/webpack-dev-middleware/releases/tag/v7.4.6' label: disclosure@vulncheck.com - url: 'https://github.com/webpack/webpack-dev-middleware/releases/tag/v8.3.0' label: disclosure@vulncheck.com - url: >- https://github.com/webpack/webpack-dev-middleware/security/advisories/GHSA-g84c-rxfj-3j2c label: disclosure@vulncheck.com - url: >- https://www.vulncheck.com/advisories/webpack-dev-middleware-path-traversal-via-offset-slice-on-a-non-slash-terminated-publicpath label: disclosure@vulncheck.com - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-76844' - url: 'https://github.com/webpack/webpack-dev-middleware/pull/2404' - url: 'https://github.com/advisories/GHSA-g84c-rxfj-3j2c' - url: >- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-76844.json - url: 'https://access.redhat.com/security/cve/CVE-2026-76844' - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2521896' - url: 'https://www.cve.org/CVERecord?id=CVE-2026-76844' - url: 'https://access.redhat.com/errata/RHSA-2026:69296' - url: 'https://access.redhat.com/errata/RHSA-2026:61783' - url: 'https://access.redhat.com/errata/RHSA-2026:68681' tags: - nvd - cve.org - exploit-available - ghsa - npm - csaf - vex - red-hat epss: 0.00592 epssPercentile: 0.48091 aliases: - GHSA-g84c-rxfj-3j2c ecosystem: npm exploitAvailable: true ssvc: exploitation: poc automatable: 'no' technicalImpact: partial timestamp: '2026-08-26T18:22:33.313523Z' scores: nvd: 7.4 vendor: 8.6 ingestedAt: '2026-09-24T20:51:40.221Z' --- ## Overview zlib 1.2.11 through 1.3.2 contains a heap buffer overflow: after an underlying write() fails, gz_write() returns without resetting strm.next_in, leaving it pointed at the caller's buffer. A later gz* write call then derives a position from the stale pointer and writes past a heap allocation; any write() failure reaches it, including EPIPE on a blocking descriptor, and in versions before 1.3.1.2 the failed write must be followed by a gzclearerr() call. ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges. ## Package advisory (CVE-2026-76844) Affected packages: - `webpack-dev-middleware >= 8.0.0, < 8.3.0` - `webpack-dev-middleware < 7.4.5` Patched in: - `webpack-dev-middleware 8.3.0` - `webpack-dev-middleware 7.4.6` Source: https://github.com/advisories/GHSA-g84c-rxfj-3j2c ## Vendor advisories - **RHSA-2026:69296** · Red Hat · fixed in: Red Hat Data Grid 8.6.3 · released 2026-09-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:69296) - **RHSA-2026:61783** · Red Hat · fixed in: Red Hat Discovery 2 · released 2026-08-31 · [advisory](https://access.redhat.com/errata/RHSA-2026:61783) - **RHSA-2026:68681** · Red Hat · fixed in: Red Hat Migration Toolkit 1.8 · released 2026-09-17 · [advisory](https://access.redhat.com/errata/RHSA-2026:68681) - **Red Hat VEX** · Important · affected: Node HealthCheck Operator, OpenShift Pipelines, Red Hat Ansible Automation Platform 2, Red Hat build of Apache Camel - HawtIO 4, Red Hat Build of Podman Desktop, Red Hat Ceph Storage 4, … · no fix planned: Red Hat Ansible Automation Platform 2, Red Hat build of Apache Camel - HawtIO 4, Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat Fuse 7, … · updated 2026-10-15 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-76844.json)