Infinite loop in Stephan Muelle libkcapi
Priority LOW 23CWE-835Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 6 fixed, 2 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-835.
Summary
A flaw was found in libkcapi. A local attacker can influence an application that uses the Asynchronous Input/Output (AIO) interface. By reusing an AIO-enabled handle after a prior completion error, the _kcapi_aio_read_all() function can enter a non-terminating wait loop. This can lead to a persistent denial of service, making the affected application or thread unresponsive.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00197 9th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Partial libkcapi (Stephan Muelle): 1.5.1Red Hat: 6 advisoriesRed Hat: 6 fixed, 2 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Stephan Muelle | libkcapi | 0.12.0 to before 1.5.1 | 1.5.1 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 10 | — | 1.5.1-1.el10_2 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 10.0 Extended Update Support | — | 1.5.0-6.el10_0 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 8 | — | 1.4.0-3.el8_10 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 9 | — | 1.4.0-3.el9_8 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 9.6 Extended Update Support | — | 1.4.0-2.el9_6.1 | Patch available | CNA |
| Red Hat | Red Hat Hardened Images | — | 1.5.1-0.1.hum1 | Patch available | CNA |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — | No fix listed | CNA |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — | No fix listed | CNA |
| Red Hat | Red Hat OpenShift Container Platform 5 | — | — | No fix listed | CNA |
- libkcapi VendorStephan Muelle Affected 0.12.0 to before 1.5.1 Fixed in 1.5.1 Patch available CNA
- Red Hat Enterprise Linux 10 VendorRed Hat Affected — Fixed in 1.5.1-1.el10_2 Patch available CNA
- Red Hat Enterprise Linux 10.0 Extended Update Support VendorRed Hat Affected — Fixed in 1.5.0-6.el10_0 Patch available CNA
- Red Hat Enterprise Linux 8 VendorRed Hat Affected — Fixed in 1.4.0-3.el8_10 Patch available CNA
- Red Hat Enterprise Linux 9 VendorRed Hat Affected — Fixed in 1.4.0-3.el9_8 Patch available CNA
- Red Hat Enterprise Linux 9.6 Extended Update Support VendorRed Hat Affected — Fixed in 1.4.0-2.el9_6.1 Patch available CNA
- Red Hat Hardened Images VendorRed Hat Affected — Fixed in 1.5.1-0.1.hum1 Patch available CNA
- Red Hat OpenShift Container Platform 4 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat OpenShift Container Platform 4 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat OpenShift Container Platform 5 VendorRed Hat Affected — Fixed in — No fix listed CNA
CPE configurations NVD · 6
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:redhat:hardened_images:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | Red Hat |
| cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:* | 4.0 | Vulnerable | Red Hat |
| cpe:2.3:a:smuellerdd:libkcapi:*:*:*:*:*:*:*:* | 0.12.0 to before 1.5.1 | Vulnerable | smuellerDD |
| cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* | 8.0 | Vulnerable | Red Hat |
| cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:* | 9.0 | Vulnerable | Red Hat |
| cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:* | 10.0 | Vulnerable | Red Hat |
- cpe:2.3:a:redhat:hardened_images:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Red Hat
- cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:* Versions 4.0 Vulnerable ·Red Hat
- cpe:2.3:a:smuellerdd:libkcapi:*:*:*:*:*:*:*:* Versions 0.12.0 to before 1.5.1 Vulnerable ·smuellerDD
- cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* Versions 8.0 Vulnerable ·Red Hat
- cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Red Hat
- cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:* Versions 10.0 Vulnerable ·Red Hat
Remediation
- Fix · CNA libkcapi (Stephan Muelle) Fixed in 1.5.1
Red Hat 6 advisories
- RHSA-2026:87712 Released 2026-10-22 · Red Hat rating Moderatelibkcapi security update
- Red Hat Enterprise Linux BaseOS EUS (v.9.6) libkcapi-1.4.0-2.el9_6.1, libkcapi-hmaccalc-1.4.0-2.el9_6.1
- RHSA-2026:69285 Released 2026-09-21 · Red Hat rating Moderatelibkcapi security update
- Red Hat Enterprise Linux BaseOS EUS (v. 10.0) libkcapi-1.5.0-6.el10_0
- RHSA-2026:67265 Released 2026-09-14 · Red Hat rating Moderatelibkcapi security, bug fix, and enhancement update
- Red Hat Enterprise Linux BaseOS (v. 9) libkcapi-1.4.0-3.el9_8, libkcapi-hmaccalc-1.4.0-3.el9_8
Show 3 more Red Hat advisories
- RHSA-2026:67267 Released 2026-09-14 · Red Hat rating Moderatelibkcapi security, bug fix, and enhancement update
- Red Hat Enterprise Linux BaseOS (v. 10) libkcapi-1.5.1-1.el10_2, libkcapi-hasher-1.5.1-1.el10_2, libkcapi-hmaccalc-1.5.1-1.el10_2
- RHSA-2026:67266 Released 2026-09-14 · Red Hat rating Moderatelibkcapi security update
- Red Hat Enterprise Linux BaseOS (v. 8) libkcapi-1.4.0-3.el8_10, libkcapi-hmaccalc-1.4.0-3.el8_10
- RHSA-2026:56985 Released 2026-08-19 · Red Hat rating ModerateRed Hat Hardened Images RPMs Security Update
- Red Hat Hardened Images libkcapi-1.5.1-0.1.hum1@aarch64, libkcapi-1.5.1-0.1.hum1@src, libkcapi-1.5.1-0.1.hum1@x86_64 +14
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Advisory ·
Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support and 7 more products — RHSA-2026:56985
3 records Highest priority Priority LOW 3 LOW
Other records, highest priority first
- TI-2026-49900 Libkcapi: memory corruption via uncanceled aio requests on error in libkcapi's one-shot aio pathPriority LOW 31
- TI-2026-49899 Libkcapi: iv reuse in libkcapi one-shot symmetric cipher chunking causes cipher state reset across chunk boundariesPriority LOW 29
- Advisory ·
Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support and 7 more products — RHSA-2026:67265
3 records Highest priority Priority LOW 3 LOW
Other records, highest priority first
- TI-2026-49900 Libkcapi: memory corruption via uncanceled aio requests on error in libkcapi's one-shot aio pathPriority LOW 31
- TI-2026-49899 Libkcapi: iv reuse in libkcapi one-shot symmetric cipher chunking causes cipher state reset across chunk boundariesPriority LOW 29
Show 4 more groups
- Advisory ·
Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support and 7 more products — RHSA-2026:67266
3 records Highest priority Priority LOW 3 LOW
Other records, highest priority first
- TI-2026-49900 Libkcapi: memory corruption via uncanceled aio requests on error in libkcapi's one-shot aio pathPriority LOW 31
- TI-2026-49899 Libkcapi: iv reuse in libkcapi one-shot symmetric cipher chunking causes cipher state reset across chunk boundariesPriority LOW 29
- Advisory ·
Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support and 7 more products — RHSA-2026:67267
3 records Highest priority Priority LOW 3 LOW
Other records, highest priority first
- TI-2026-49900 Libkcapi: memory corruption via uncanceled aio requests on error in libkcapi's one-shot aio pathPriority LOW 31
- TI-2026-49899 Libkcapi: iv reuse in libkcapi one-shot symmetric cipher chunking causes cipher state reset across chunk boundariesPriority LOW 29
- Advisory ·
Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support and 7 more products — RHSA-2026:69285
3 records Highest priority Priority LOW 3 LOW
Other records, highest priority first
- TI-2026-49900 Libkcapi: memory corruption via uncanceled aio requests on error in libkcapi's one-shot aio pathPriority LOW 31
- TI-2026-49899 Libkcapi: iv reuse in libkcapi one-shot symmetric cipher chunking causes cipher state reset across chunk boundariesPriority LOW 29
- Advisory ·
Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support and 7 more products — RHSA-2026:87712
3 records Highest priority Priority LOW 3 LOW
Other records, highest priority first
- TI-2026-49900 Libkcapi: memory corruption via uncanceled aio requests on error in libkcapi's one-shot aio pathPriority LOW 31
- TI-2026-49899 Libkcapi: iv reuse in libkcapi one-shot symmetric cipher chunking causes cipher state reset across chunk boundariesPriority LOW 29
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux BaseOS (v. 10) | Fixed | RHSA-2026:67267 |
| Red Hat Enterprise Linux BaseOS (v. 8) | Fixed | RHSA-2026:67266 |
| Red Hat Enterprise Linux BaseOS (v. 9) | Fixed | RHSA-2026:67265 |
| Red Hat Enterprise Linux BaseOS EUS (v. 10.0) | Fixed | RHSA-2026:69285 |
| Red Hat Enterprise Linux BaseOS EUS (v.9.6) | Fixed | RHSA-2026:87712 |
| Red Hat Hardened Images | Fixed | RHSA-2026:56985 |
Not affected: 2 products
- Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
- Red Hat Enterprise Linux BaseOS EUS (v.9.6)
Timeline
- 2026-10-02 Threatist record created from CVE-2026-71227
- 2026-10-03 Alias added: GHSA-c5mv-c5vm-62w5
- 2026-10-23 Fix available: libkcapi@0:1.4.0-2.el9_6.1 · CNA
- 2026-10-23 1 new reference · CNA
- 2026-10-23 Fix available: RHSA-2026:87712 · Red Hat
- 2026-10-23 Fix available: Red Hat Enterprise Linux BaseOS EUS (v.9.6) · Red Hat
- 2026-11-02 Affected versions changed · CNA
- 2026-11-02 Affected versions changed · Red Hat
References
More Red Hat Enterprise Linux vulnerabilities
- TI-2019-08259 Underflow in PHP-FPM can lead to RCE KEVCVSS 3.1CRITICAL 9.8
- TI-2018-10530 Code injection in [UNKNOWN] RichFaces KEVCVSS 3.1CRITICAL 9.8
- TI-2014-05975 GNU Bash through 4.3 bash43-025 processes trailing strings after certain malformed… KEVCVSS 3.1CRITICAL 9.8
- TI-2014-05157 GNU Bash through 4.3 processes trailing strings after function definitions in the values… KEVCVSS 3.1CRITICAL 9.8
- TI-2025-23530 Sudo before 1.9.17p1 allows local users to obtain root access because /etc/nsswitch.conf… KEVCVSS 3.1CRITICAL 9.3
- TI-2021-17490 mod_proxy SSRF KEVCVSS 3.1CRITICAL 9.0
Sources
- CVE-2026-71227 · CVE Program
- CVE-2026-71227 · NVD
- FIRST EPSS
- GHSA-c5mv-c5vm-62w5 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-71227 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences