lz4_flex: Insertion of Sensitive Information Into Sent Data
CVE-2026-32829 is a high-severity insertion of sensitive information into sent data vulnerability in lz4_flex from PSeitz, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected lz4_flex versions: < 0.11.6; >= 0.12.0, < 0.12.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.63% chance of exploitation within 30 days, higher than 51% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of lz4_flex you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| PSeitz | lz4_flex | < 0.11.6; >= 0.12.0, < 0.12.1 | Not stated |
| Red Hat | Logging Subsystem for Red Hat OpenShift 6.2 | Not specified in the record | Not stated |
| Red Hat | Logging Subsystem for Red Hat OpenShift 6.4 | Not specified in the record | Not stated |
| Red Hat | Logging Subsystem for Red Hat OpenShift 6.5 | Not specified in the record | Not stated |
| Red Hat | Red Hat OpenShift AI 3.3 | Not specified in the record | Not stated |
| Red Hat | OpenShift Lightspeed | Not specified in the record | Not stated |
| Red Hat | Red Hat Ansible Automation Platform 2 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 10 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 9 | Not specified in the record | Not stated |
| Red Hat | Red Hat OpenShift AI (RHOAI) | Not specified in the record | Not stated |
Version data comes from the organisation that assigned the CVE. 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
- NoneNothing can be modified.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.2 | High | CNA (github.com) |
| CVSS 3.1 | 7.5 | High | NVD |
| CVSS 3.1 | 7.5 | High | CNA |
Official description
lz4_flex is a pure Rust implementation of LZ4 compression/decompression. In versions 0.11.5 and below, and 0.12.0, decompressing invalid LZ4 data can leak sensitive information from uninitialized memory or from previous decompression operations. The library fails to properly validate offset values during LZ4 "match copy operations," allowing out-of-bounds reads from the output buffer. The block-based API functions (`decompress_into`, `decompress_into_with_dict`, and others when `safe-decode` is disabled) are affected, while all frame APIs are unaffected. The impact is potential exposure of sensitive data and secrets through crafted or malformed LZ4 input. This issue has been fixed in versions 0.11.6 and 0.12.1.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Insertion of Sensitive Information Into Sent Data
The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor.
How developers prevent this class of flaw
- Specify which data in the software should be regarded as sensitive. Consider which types of users should have access to which types of data.
- Ensure that any possibly sensitive data specified in the requirements is verified with designers to ensure that it is either a calculated risk or mitigated elsewhere. Any information that is not necessary to the functionality should be removed in order to lower both the overhead and the possibility of security sensitive data being sent.
- Setup default error messages so that unexpected errors do not disclose sensitive information.
More Insertion of Sensitive Information Into Sent Data vulnerabilities (CWE-201)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Patches and release notes
Third-party and government advisories
- rustsec.org/advisories/RUSTSEC-2026-0041.htmlThird Party Advisory
Other references
- access.redhat.com/errata/RHSA-2026:11800
- access.redhat.com/errata/RHSA-2026:16354
- access.redhat.com/errata/RHSA-2026:19712
- access.redhat.com/errata/RHSA-2026:22862
- access.redhat.com/security/cve/CVE-2026-32829
- bugzilla.redhat.com/show_bug.cgi?id=2448271
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-32829.json
Recent Insertion of Sensitive Information Into Sent Data vulnerabilities
- 7.5 High severity
- 8.7 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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