redis: Use After Free
CVE-2026-23631 is a high-severity use after free vulnerability in redis, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected redis versions: < 8.6.3. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 3.09% chance of exploitation within 30 days, higher than 88% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of redis 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.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Redis | redis | < 8.6.3 | Not stated |
| Red Hat | Red Hat Enterprise Linux 10 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 10.0 Extended Update Support | 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 Enterprise Linux 9.4 Update Services for SAP Solutions | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 9.6 Extended Update Support | Not specified in the record | Not stated |
| Red Hat | Red Hat Hardened Images | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 8 | 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
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- 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:L/UI:N/S:U/C:N/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 6.1 | Medium | CNA (github.com) |
| CVSS 3.1 | 8.1 | High | NVD |
| CVSS 3.1 | 8.8 | High | CNA |
Official description
Redis is an in-memory data structure store. In all versions of redis-server with Lua scripting, an authenticated attacker can exploit the master-replica synchronization mechanism to trigger a use-after-free on replicas where replica-read-only is disabled or can be disabled, which may lead to remote code execution. A workaround is to prevent users from executing Lua scripts or avoid using replicas where replica-read-only is disabled. This is patched in version 8.6.3.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Patches and release notes
- github.com/redis/redis/releases/tag/8.6.3Release Notes
Other references
- access.redhat.com/errata/RHSA-2026:14316
- access.redhat.com/errata/RHSA-2026:25216
- access.redhat.com/errata/RHSA-2026:25219
- access.redhat.com/errata/RHSA-2026:25925
- access.redhat.com/errata/RHSA-2026:26306
- access.redhat.com/errata/RHSA-2026:26540
- access.redhat.com/errata/RHSA-2026:33444
- access.redhat.com/security/cve/CVE-2026-23631
- bugzilla.redhat.com/show_bug.cgi?id=2466788
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23631.json
Other vulnerabilities in redis
- 7.1 High severity
- 7.5 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 9.9 Critical severity
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 8.1 High severity
- 8.1 High severity
- 7.8 High severity
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