synced 10 MIN AGO
01 Record

CVE-2026-66046

Expat Denial of Service via storeAtts() Quadratic Complexity

HighPUBLISHEDCNA: VulnCheck
CNA base score8.7 CVSS v4.0CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
View raw JSON

02 Description

Expat Denial of Service via storeAtts() Quadratic Complexity

03 Exploitation and scoring

Exploitation
Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
SSVC decision
  • ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
  • AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.74% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 54.3% of scored records. A rank, not a probability.
NVD base score
8.7 (CVSS v4.0), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/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
NVD analysis status
Analyzed. NVD last modified this record on 2026-10-22.
Red Hat severity
Important. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-08-18 14:10Z2 MO AGO
Last updated
2026-10-01 15:20Z28 DAYS AGO
Reserved
2026-07-23
Assigning CNA
VulnCheck
Record state
PUBLISHED
Severity
High (CVSS 8.7)
CNA CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weaknesses
  • CWE-407Inefficient Algorithmic ComplexityClass
Data version
5.2
Document digest
317069ef9899c6d0e25c93e7fae89482b2ced29ff08b0d509fa94087e9fb6909

05 Affected products

VendorProductVersionsPlatforms
libexpat projectlibexpat0 to 2.8.3—

06 References

07 Fixed in

AlmaLinux 8

  • expat
    Fixed in 2.5.0-4.el8_10
  • expat-devel
    Fixed in 2.5.0-4.el8_10

Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

AlmaLinux 9

  • expat
    Fixed in 2.5.0-6.el9_8.5
  • expat-devel
    Fixed in 2.5.0-6.el9_8.5

Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

AlmaLinux 10

  • expat
    Fixed in 2.7.3-1.el10_2.5
  • expat-devel
    Fixed in 2.7.3-1.el10_2.5

Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

CloudLinux 8

  • expat
    Fixed in 2.5.0-4.el8_10
  • expat-devel
    Fixed in 2.5.0-4.el8_10

Derived from AlmaLinux 8. Partial coverage: only packages taken from AlmaLinux 8 are listed.

Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

CloudLinux 9

  • expat
    Fixed in 2.5.0-6.el9_8.5
  • expat-devel
    Fixed in 2.5.0-6.el9_8.5

Derived from AlmaLinux 9. Partial coverage: only packages taken from AlmaLinux 9 are listed.

Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

CloudLinux 10

  • expat
    Fixed in 2.7.3-1.el10_2.5
  • expat-devel
    Fixed in 2.7.3-1.el10_2.5

Derived from AlmaLinux 10. Partial coverage: only packages taken from AlmaLinux 10 are listed.

Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

Debian 12

  • expat
    Fixed in 2.5.0-1+deb12u4

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

  • expat
    Fixed in 2.9.0-1~deb13u1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

  • expat
    Fixed in 2.8.4-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 16.04 LTS

  • cadaver
    No fix yet
  • insighttoolkit4
    No fix yet
  • matanza
    No fix yet
  • smart
    No fix yet
  • tdom
    No fix yet
  • wbxml2
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 18.04 LTS

  • cadaver
    No fix yet
  • insighttoolkit4
    No fix yet
  • matanza
    No fix yet
  • smart
    No fix yet
  • tdom
    No fix yet
  • vnc4
    No fix yet
  • wbxml2
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 20.04 LTS

  • cadaver
    No fix yet
  • insighttoolkit4
    No fix yet
  • matanza
    No fix yet
  • tdom
    No fix yet
  • wbxml2
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 22.04 LTS

  • cadaver
    No fix yet
  • expat
    Fixed in 2.4.7-1ubuntu0.9
  • insighttoolkit4
    No fix yet
  • matanza
    No fix yet
  • tdom
    No fix yet
  • wbxml2
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 24.04 LTS

  • cadaver
    No fix yet
  • expat
    Fixed in 2.6.1-2ubuntu0.6
  • matanza
    No fix yet
  • tdom
    No fix yet
  • wbxml2
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 26.04 LTS

  • cadaver
    No fix yet
  • expat
    Fixed in 2.7.4-1ubuntu0.2
  • matanza
    No fix yet
  • tdom
    No fix yet
  • wbxml2
    No fix yet
  • xmlrpc-c
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 26.10

  • cadaver
    No fix yet
  • matanza
    No fix yet
  • swish-e
    No fix yet
  • tdom
    No fix yet
  • wbxml2
    No fix yet
  • xmlrpc-c
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 14.04 LTS

  • coin3
    No fix yet
  • expat
    Fixed in 2.1.0-4ubuntu1.4+esm13
    Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro
  • vnc4
    No fix yet
  • vtk
    No fix yet
  • xmlrpc-c
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 16.04 LTS

  • ayttm
    No fix yet
  • cableswig
    No fix yet
  • coin3
    No fix yet
  • expat
    Fixed in 2.1.0-7ubuntu0.16.04.5+esm14
    Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro
  • libxmltok
    No fix yet
  • swish-e
    No fix yet
  • vnc4
    No fix yet
  • vtk
    No fix yet
  • xmlrpc-c
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 18.04 LTS

  • coin3
    No fix yet
  • expat
    Fixed in 2.2.5-3ubuntu0.9+esm5
    Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro
  • libxmltok
    No fix yet
  • swish-e
    No fix yet
  • xmlrpc-c
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 20.04 LTS

  • expat
    Fixed in 2.2.9-1ubuntu0.8+esm3
    Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro
  • libxmltok
    No fix yet
  • swish-e
    No fix yet
  • xmlrpc-c
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 22.04 LTS

  • libxmltok
    No fix yet
  • swish-e
    No fix yet
  • xmlrpc-c
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 24.04 LTS

  • libxmltok
    No fix yet
  • swish-e
    No fix yet
  • xmlrpc-c
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 26.04 LTS

  • swish-e
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.