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CVE-2026-111497: Google Brotli Unchecked Return Value Vulnerability
CVE-2026-111497 is rated critical with a CVSS v3.1 base score of 9.8 and affects Google Brotli, along with 22 other products in NVD’s configuration data. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available. CISA added it to its Known Exploited Vulnerabilities catalog on 2026-10-27, which means exploitation in the wild has been observed.
Vulnerability description
A buffer overflow vulnerability in the Brotli decoder (c/dec/decode.c) in Google Brotli versions 1.0.3 through 1.2.0 on all platforms allows a remote unauthenticated attacker to corrupt adjacent decoder state memory, disclose sensitive memory contents, cause a denial of service, or potentially execute arbitrary code using a crafted Brotli-compressed stream. Users need to update any Brotli libraries or binaries between 1.0.3 through 1.2.0 to the latest available version: 1.0.10 or 1.1.1 or 1.2.1.
Severity breakdown
CVSS v3.1 9.8: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
- Attack complexity: Low. No special conditions; the attack can be repeated reliably.
- Privileges required: None. No account or prior access is needed.
- User interaction: None. No action from any user is needed.
- Scope: Unchanged. Impact stays within the vulnerable component.
- Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
- Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
- Availability impact: High. Total loss of availability; the component can be shut down.
Underlying weakness
CWE-252: Unchecked Return Value
The product does not check the return value from a method or function.
CWE-787: Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.
Affected products
- Google Brotli: from 1.0.3 before 1.0.10; from 1.1.0 before 1.1.1; from 1.2.0 before 1.2.1
- Python Hyper Brotlicffi: before 1.2.1.0
- Andybalholm Brotli: before 1.2.7
- Node.Js: before 22.23.4; from 23.0.0 before 24.22.1; from 25.0.0 before 26.12.1
- Microsoft .Net: from 8.0.0 before 8.0.33; from 9.0.0 before 9.0.22; from 10.0.0 before 10.0.14; 11.0.0 preview1; 11.0.0 preview2; 11.0.0 preview3; 11.0.0 preview4; 11.0.0 preview5; 11.0.0 preview6; 11.0.0 preview7; 11.0.0 rc1; 11.0.0 rc2
- Debian Linux: 12.0
- Istio: before 1.29.9; from 1.30.0 before 1.30.6; from 1.31.0 before 1.31.2
- Anthropic Bun: before 1.4.4
- Envoyproxy: before 1.37.8; from 1.38.0 before 1.38.6; from 1.39.0 before 1.39.3
- Tianocore Edk2: up to and including 202608
- Google Woff2: all versions listed by NVD
- Duckdb: up to and including 2.0.0
- Clickhouse: up to and including 26.10.2.103
- Apache Arrow: up to and including 26.0.0; 27.0.0 dev
- Mcmilk 7 Zip Zstd: up to and including 26.02-1.5.7-r2
References
- https://github.com/dotnet/announcements/issues/494
- https://nodejs.org/en/blog/vulnerability/october-2026-security-releases#nodejs-brotli-decoder-out-of-bounds-write-permits-remote-code-execution-cve-2026-111497---high
- http://www.openwall.com/lists/oss-security/2026/10/23/25
- http://www.openwall.com/lists/oss-security/2026/10/24/6
- http://www.openwall.com/lists/oss-security/2026/10/26/12
- http://www.openwall.com/lists/oss-security/2026/10/26/13
- http://www.openwall.com/lists/oss-security/2026/10/26/16
- http://www.openwall.com/lists/oss-security/2026/11/03/2
- https://broccoli2shell.com
- https://github.com/advisories/GHSA-9v8h-qqgm-4m35
- https://lists.debian.org/debian-lts-announce/2026/10/msg00049.html
- https://patchtheplanet.org/brotli
- https://www.aikido.dev/blog/node2shell-nodejs-brotli-rce-cve-2026-111497
- https://cert-portal.siemens.com/productcert/html/ssa-045512.html