LowCVE-2026-82631

    valkey-io valkey Blocked-on-keys blocked.c handleClientsBlockedOnKey use after free (CVE-2026-82631)

    Published Last modified Sources: Debian, Msrc Update Guide, CVE.org

    What is affected, what to do

    A security flaw has been discovered in valkey-io valkey 9.1.0. The affected element is the function handleClientsBlockedOnKey of the file src/blocked.c of the component Blocked-on-keys Subsystem.

    An exploit is publicly available. The available sources name no fixed version. Check the vendor guidance in the references below.

    Affected
    • Valkey eq 9.1.0..9.1.0

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    2.2

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    2.2

    CVSS v3

    Severity Low on the scale from 0 to 10.

    Source: Debian, Msrc Update Guide, CVE.org

    0.4 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 29.7

    Show all metrics
    Severity
    Low
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    42.63 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    PoC (publicly reported)
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    2.2 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    2.2
    CVSS v4

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    2.1
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    0.4 %
    Low — model estimates < 1% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    29.7
    Elevated — this CVE ranks above at least 10% of all CVEs scored today.
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    —
    Published
    CISA assessment (SSVC)
    Exploitation: proof of concept · not automatable · Technical impact: partial
    Source: CISA Vulnrichment, as of 31 August 2026
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-416, CWE-119

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    A security flaw has been discovered in valkey-io valkey 9.1.0. The affected element is the function handleClientsBlockedOnKey of the file src/blocked.c of the component Blocked-on-keys Subsystem. The manipulation results in use after free. The attack may be performed from remote. A high complexity level is associated with this attack. The exploitability is described as difficult. The exploit has been released to the public and may be used for attacks. The patch is identified as b2fb0e13f5b4c8c2fb63dcfc2c37a067a0d6d20b. Applying a patch is advised to resolve this issue.

    Source: Debian Security Advisories, Microsoft Security Update Guide, NVD (NIST), cvelistv5

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    valkey-iovalkey
    • 9.1.0
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianvalkeytrixie

    Weakness classes (CWE)

    • CWE-416Use After Free

      Variant

      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.

      Entry at MITRE CWE-416

    • CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer

      Class

      The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.

      Entry at MITRE CWE-119

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    Reference tagged as exploitgithub.com (opens in a new tab)PoC (publicly reported)reported, not verified—

    References & sources

    • vuldb.comVDB-397129 | valkey-io valkey Blocked-on-keys blocked.c handleClientsBlockedOnKey use after freeVulnerability database, Technical description
    • vuldb.comVDB-397129 | CTI Indicators (IOB, IOC, IOA)signature, Permissions required
    • vuldb.comCVE-2026-82631 | CVE Analysis and ReportThird-party advisory
    • vuldb.comSubmit #893793 | Valkey Project Valkey 9.1.0 Heap Use After FreeThird-party advisory
    • github.comvalkey-io/valkey/issues/4198Issue tracking
    • github.comvalkey-io/valkey/pull/4212Issue tracking, Patch
    • github.comuser-attachments/files/30111628/PoC.zipExploit
    • github.comvalkey-io/valkey/commit/b2fb0e13f5b4c8c2fb63dcfc2c37a067a0d6d20bPatch
    • github.comvalkey-io/valkeyProduct

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: proof of concept, automatable: no

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      SSVC assessmentadded
      —
      {"id":"CVE-2026-82631","role":"CISA Coordinator","options":[{"exploitation":"poc"},{"automatable":"no"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-08-31T11:22:07.646542Z"}

      Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

    2. ReceivedVulDB

      CVSS V4.0: AV:N/AC:H/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P

      CVSS V3.1: AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L

      CVSS V2: (AV:N/AC:H/Au:M/C:N/I:N/A:P)

      Weakness type: CWE-119, CWE-416

      Description added or changed

      Show 16 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      A security flaw has been discovered in valkey-io valkey 9.1.0. The affected element is the function handleClientsBlockedOnKey of the file src/blocked.c of the component Blocked-on-keys Subsystem. The manipulation results in use after free. The attack may be performed from remote. A high complexity level is associated with this attack. The exploitability is described as difficult. The exploit has been released to the public and may be used for attacks. The patch is identified as b2fb0e13f5b4c8c2fb63dcfc2c37a067a0d6d20b. Applying a patch is advised to resolve this issue.
      CVSSadded
      —
      AV:N/AC:H/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
      CVSSadded
      —
      AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L
      CVSSadded
      —
      (AV:N/AC:H/Au:M/C:N/I:N/A:P)
      Weakness type (CWE)added
      —
      CWE-119
      Weakness type (CWE)added
      —
      CWE-416
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/82xxx/CVE-2026-82631.json">CVE-2026-82631</a>
      Referenceadded
      —
      https://github.com/user-attachments/files/30111628/PoC.zip
      Referenceadded
      —
      https://github.com/valkey-io/valkey/
      Referenceadded
      —
      https://github.com/valkey-io/valkey/commit/b2fb0e13f5b4c8c2fb63dcfc2c37a067a0d6d20b
      Referenceadded
      —
      https://github.com/valkey-io/valkey/issues/4198
      Referenceadded
      —
      https://github.com/valkey-io/valkey/pull/4212
      Referenceadded
      —
      https://vuldb.com/cve/CVE-2026-82631
      Referenceadded
      —
      https://vuldb.com/submit/893793
      Referenceadded
      —
      https://vuldb.com/vuln/397129
      Referenceadded
      —
      https://vuldb.com/vuln/397129/cti

      Source identifier: cna@vuldb.com

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