CyberSecBulletin
CVE-2026-111497Exploited in the wildNVD status: Analyzed

Google Brotli Unchecked Return Value

Published Updated By the CyberSecBulletin desk

CVE-2026-111497 is a critical-severity unchecked return value vulnerability in Brotli from Google, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 1.0.10, 1.1.1, 1.2.1 as the first without the flaw, so updating Brotli to one of those releases or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on October 27, 2026, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Update Brotli to 1.0.10 or 1.1.1 or 1.2.1, whichever matches your release line, or a later version.
  2. Update Cloud Connector Configurator to V1.24.3 or a later version.
  3. Update Data Flow Monitoring to V3.0.18 or a later version.
  4. CISA's required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
  5. Read the advisory on github.com for workarounds and exact fixed builds.
  6. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
GoogleBrotli1.0.3 up to, but not including, 1.0.10; 1.1.0 up to, but not including, 1.1.1; 1.2.0 up to, but not including, 1.2.11.0.10, 1.1.1, 1.2.1
SiemensCalibreNot specified in the recordNot stated
SiemensCalibre ICENot specified in the recordNot stated
SiemensCapitalNot specified in the recordNot stated
SiemensCloud Connector Configuratorbefore V1.24.3V1.24.3
SiemensCommon Configurator (CC on IEM)all versionsNot stated
SiemensCommon Configurator on Device (CC on Edge)all versionsNot stated
SiemensCOMOS Walkinsideall versionsNot stated
SiemensData Flow Monitoringbefore V3.0.18V3.0.18
SiemensDatabus Configuratorbefore V4.0.1V4.0.1
SiemensDataXess Configuratorbefore V1.5.7V1.5.7
SiemensDesigncenter X EssentialsNot specified in the recordNot stated
SiemensDesigo CC family V8all versionsNot stated
SiemensDesigo CC family V9all versionsNot stated
SiemensEdge OPC UA Server Configuratorbefore V2.3.10V2.3.10
SiemensFlow Creator Configuratorbefore V1.15.1V1.15.1
SiemensgDAP (gPROMS Digital Application Platform)Not specified in the recordNot stated
SiemensGridscale X DSAV5.3 up to, but not including, V5.4V5.4
SiemensGridscale X PSS®Ebefore V36.8.0V36.8.0
SiemensHeliox Dual Port 60kWNot specified in the recordNot stated
SiemensHeliox Flex ProNot specified in the recordNot stated
SiemensHyperLynxall versionsNot stated
SiemensIndustrial Edge Huball versionsNot stated
SiemensIndustrial Edge Management Cloudall versionsNot stated
SiemensInnexis Architecture Native Acceleration 2026all versionsNot stated

Version data comes from the organisation that assigned the CVE; 35 further products are omitted here. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 4.09.2CriticalCNA (google.com)
CVSS 3.19.8CriticalNVD

Official 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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Unchecked Return Value

The product does not check the return value from a method or function.

How developers prevent this class of flaw

  • Check the results of all functions that return a value and verify that the value is expected.
  • For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished.
  • Ensure that you account for all possible return values from the function.

More Unchecked Return Value vulnerabilities (CWE-252)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
  3. Added to CISA's Known Exploited Vulnerabilities catalogue.
  4. Record last changed materially (score, affected products, status or references).
  5. Deadline for US federal agencies to remediate, set by CISA.

References

Advisories

Third-party and government advisories

Our coverage

Recent Unchecked Return Value vulnerabilities

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