HighCVE-2026-82760

    Superlinear base62 decoding exhausts CPU and memory in AshAuthentication API key sign-in (CVE-2026-82760)

    Published Last modified Sources: CVE.org, OSV

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    What is affected, what to do

    Inefficient Algorithmic Complexity vulnerability in team-alembic AshAuthentication allows an unauthenticated attacker to exhaust CPU and memory via an oversized base62 segment in a submitted API key. AshAuthentication.Base.decode62/1 in lib/ash_authentication/base.ex splits its argument into one binary per character and folds it with charval62/2, which recomputes Integer.pow(62, index) at every position instead of accumulating by Horner's method, so cost grows roughly cubically in the input length. bindecode62/1 in the same module is quadratic through Integer.undigits/2 and Integer.digits/2.

    Update Team-alembic Ash Authentication to version 4.15.0, Team-alembic Ash Authentication to version 5.0.0-rc.14.

    Affected
    • Team-alembic Ash Authentication lt 4.8.0..4.15.0
    • Team-alembic Ash Authentication lt 5.0.0-rc.0..5.0.0-rc.14
    Fixed in
    • Team-alembic Ash Authentication 4.15.0
    • Team-alembic Ash Authentication 5.0.0-rc.14

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

    Metrics

    8.2

    Priority

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

    Source: Vendor (CNA), CVSS v4

    8.2

    CVSS v4

    Severity High on the scale from 0 to 10.

    Source: CVE.org, OSV

    0.7 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 54.6

    Show all metrics
    Severity
    High
    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
    91.20 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
    no public PoC known
    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
    8.2 Methodology
    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
    8.2
    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
    0.7 %
    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
    54.6
    High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
    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: none known · not automatable · Technical impact: partial
    Source: CISA Vulnrichment, as of 17 September 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-407

    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
    High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
    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

    Inefficient Algorithmic Complexity vulnerability in team-alembic AshAuthentication allows an unauthenticated attacker to exhaust CPU and memory via an oversized base62 segment in a submitted API key. AshAuthentication.Base.decode62/1 in lib/ash_authentication/base.ex splits its argument into one binary per character and folds it with charval62/2, which recomputes Integer.pow(62, index) at every position instead of accumulating by Horner's method, so cost grows roughly cubically in the input length. bindecode62/1 in the same module is quadratic through Integer.undigits/2 and Integer.digits/2. Neither function caps byte_size/1, and AshAuthentication.Strategy.ApiKey.SignInPreparation passes the underscore-separated segments of the submitted key straight into both, before any key lookup and without prior authentication. The surrounding rescue clauses catch exceptions, not CPU or memory exhaustion. This issue affects ash_authentication: from 4.8.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

    Source: NVD (NIST), OSV (Open Source Vulnerabilities), 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
    team-alembicash_authentication
    • 4.8.0 – < 4.15.0
    • 5.0.0-rc.0 – < 5.0.0-rc.14
    • 4.15.0
    • 5.0.0-rc.14
    hexash_authentication
    • 4.13.2
    • 4.9.6
    • 4.9.9
    • 4.14.2
    • 4.13.5
    • 5.0.0-rc.5
    • 4.9.0
    • 4.8.2
    • 5.0.0-rc.7
    • 5.0.0-rc.6
    • 4.8.7
    • 4.14.1
    • 4.8.6
    • 4.9.1
    • 5.0.0-rc.3
    • 5.0.0-rc.4
    • 4.13.7
    • 5.0.0-rc.12
    • 4.8.5
    • 4.8.3
    • 4.9.5
    • 4.13.0
    • 4.13.6
    • 4.8.1
    • 4.10.0
    • 5.0.0-rc.8
    • 4.12.0
    • 4.13.1
    • 4.9.2
    • 5.0.0-rc.13
    • 5.0.0-rc.0
    • 5.0.0-rc.9
    • 4.9.7
    • 4.13.4
    • 5.0.0-rc.10
    • 4.9.8
    • 4.14.0
    • 4.13.3
    • 4.9.4
    • 5.0.0-rc.2
    • 5.0.0-rc.11
    • 4.9.3
    • 5.0.0-rc.1
    • 4.8.0
    • 4.11.0
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    Vendors and products

    Weakness classes (CWE)

    • CWE-407Inefficient Algorithmic Complexity

      Class

      An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.

      Entry at MITRE CWE-407

    References & sources

    • github.comteam-alembic/ash_authentication/security/advisories/GHSA-q876-x…related, Vendor advisory
    • cna.erlef.orgEEF CNA record for CVE-2026-82760related
    • OSV (Open Source Vulnerabilities)OSV record EEF-CVE-2026-82760related
    • github.comIntroducing commit f3a53f4 in team-alembic/ash_authenticationrelated
    • github.comFix commit d5a5d4c in team-alembic/ash_authenticationPatch
    • github.comFix commit dfb19c8 in team-alembic/ash_authenticationPatch
    • hex.pmpackages/ash_authenticationpackage

    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: none known, automatable: no

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      SSVC assessmentadded
      —
      {"id":"CVE-2026-82760","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-09-17T18:21:05.949151Z"}

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

    2. ReceivedEEF

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

      Weakness type: CWE-407

      Description added or changed

      Show 10 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      Inefficient Algorithmic Complexity vulnerability in team-alembic AshAuthentication allows an unauthenticated attacker to exhaust CPU and memory via an oversized base62 segment in a submitted API key. AshAuthentication.Base.decode62/1 in lib/ash_authentication/base.ex splits its argument into one binary per character and folds it with charval62/2, which recomputes Integer.pow(62, index) at every position instead of accumulating by Horner's method, so cost grows roughly cubically in the input length. bindecode62/1 in the same module is quadratic through Integer.undigits/2 and Integer.digits/2. Neither function caps byte_size/1, and AshAuthentication.Strategy.ApiKey.SignInPreparation passes the underscore-separated segments of the submitted key straight into both, before any key lookup and without prior authentication. The surrounding rescue clauses catch exceptions, not CPU or memory exhaustion. This issue affects ash_authentication: from 4.8.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.
      CVSSadded
      —
      AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/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
      Weakness type (CWE)added
      —
      CWE-407
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/82xxx/CVE-2026-82760.json">CVE-2026-82760</a>
      Referenceadded
      —
      https://cna.erlef.org/cves/CVE-2026-82760.html
      Referenceadded
      —
      https://github.com/team-alembic/ash_authentication/commit/d5a5d4cb5cc17fbd6e2a120a6111b47accad4b8e
      Referenceadded
      —
      https://github.com/team-alembic/ash_authentication/commit/dfb19c897853686ab481c5e773f7a1a0c74dea04
      Referenceadded
      —
      https://github.com/team-alembic/ash_authentication/commit/f3a53f480088419788d5c3934af3131fa9066773
      Referenceadded
      —
      https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-q876-xr24-2mcx
      Referenceadded
      —
      https://osv.dev/vulnerability/EEF-CVE-2026-82760

      Source identifier: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

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