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Fencer Vulns
high 7.5

CVE-2026-42245 json

net-imap: Quadratic complexity when reading response literals

published 2026-05-04 6 mo ago modified 2026-09-10 1 mo ago also EUVD-2026-28923 , GHSA-q2mw-fvj9-vvcw

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 35%
public exploits
0
none known

Summary

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.4.24, 0.5.14, and 0.6.4, Net::IMAP::ResponseReader has quadratic time complexity when reading large responses containing many string literals. A hostile server can send responses which are crafted to exhaust the client's CPU for a denial of service attack. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.

Patch / fix

  • rubygems net-imap 0.4.24, 0.5.14, 0.6.4
  • ruby-lang net-imap 0.4.24, 0.5.14, 0.6.4
  • ruby-lang net::imap 0.4.24, 0.5.14, 0.6.4
  • ruby3.3 Debian 13 3.3.13-0+deb13u1

debian advisories DEBIAN-CVE-2026-42245

  • ruby3.4 hummingbird 1 3.4.10-31.hum1
  • ruby3.4-libs hummingbird 1 3.4.10-31.hum1
  • rubygem3.4-irb hummingbird 1 1.14.3-31.hum1
  • rubygem3.4-rbs hummingbird 1 3.8.0-31.hum1
  • rubygem3.4-rss hummingbird 1 0.3.1-31.hum1
  • rubygem3.4-json hummingbird 1 2.9.1-31.hum1
  • rubygem3.4-racc hummingbird 1 1.8.1-31.hum1
  • rubygem3.4-rake hummingbird 1 13.2.1-31.hum1

red hat advisories RHSA-2026:38694RHSA-2026:37238RHSA-2026:36099RHSA-2026:35895RHSA-2026:33721RHSA-2026:33576

  • ruby AlmaLinux 8 3.3.10-7.module_el8.10.0+4210+b037b1ec
  • rubygems AlmaLinux 8 3.5.22-7.module_el8.10.0+4210+b037b1ec
  • ruby-libs AlmaLinux 8 3.3.10-7.module_el8.10.0+4210+b037b1ec
  • rubygem-pg AlmaLinux 8 1.5.4-1.module_el8.10.0+3799+191214cc
  • rubygem-irb AlmaLinux 8 1.13.1-7.module_el8.10.0+4210+b037b1ec
  • rubygem-rbs AlmaLinux 8 3.4.0-7.module_el8.10.0+4210+b037b1ec
  • rubygem-rss AlmaLinux 8 0.3.1-7.module_el8.10.0+4210+b037b1ec
  • rubygem-abrt AlmaLinux 8 0.4.0-1.module_el8.10.0+3799+191214cc

almalinux advisories ALSA-2026:33515ALSA-2026:33540ALSA-2026:33565ALSA-2026:33576ALSA-2026:33577

  • ruby4.0 Rocky Linux 10 4.0.3-35.el10_2
  • ruby Rocky Linux 10 3.3.10-13.el10_2
  • rubygem-pg Rocky Linux 9 1.5.4-2.module+el9.7.0+40188+314ad260.0.1
  • rubygem-mysql2 Rocky Linux 9 0.5.5-3.module+el9.7.0+40032+36e56d0d
  • rubygem-pg Rocky Linux 9 1.6.3-1.module+el9.8.0+40094+ce01217c
  • rubygem-mysql2 Rocky Linux 9 0.5.7-1.module+el9.8.0+40094+ce01217c
  • rubygem-pg Rocky Linux 8 1.5.4-1.module+el8.10.0+1679+61871737
  • rubygem-pg Rocky Linux 8 1.5.4-1.module+el8.10.0+1827+16ecb9d2

rocky linux advisories RLSA-2026:33540RLSA-2026:33565RLSA-2026:33576RLSA-2026:33577RLSA-2026:33515

  • ruby-net-imap Alpine 3.21 0.4.25-r0

alpine advisories ALPINE-CVE-2026-42245

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-42245 updated cvss 6.5

ruby: net-imap: Net::IMAP: Denial of Service via crafted IMAP responses

  • Red Hat Enterprise Linux AppStream (v. 8) ruby 3.3.10-7.module+el8.10.0+24407+4a33a056, rubygems 3.5.22-7.module+el8.10.0+24407+4a33a056, ruby-libs 3.3.10-7.module+el8.10.0+24407+4a33a056, rubygem-pg 1.5.4-1.module+el8.10.0+21226+b78a28c4, rubygem-rbs 3.4.0-7.module+el8.10.0+24407+4a33a056, rubygem-rss 0.3.1-7.module+el8.10.0+24407+4a33a056, +18 more
    fixed: vendor fix RHSA-2026:33515
  • Red Hat Enterprise Linux AppStream (v. 9) ruby 3.3.10-7.module+el9.8.0+24406+8975e57f, ruby 4.0.3-33.module+el9.8.0+24428+77f1d00a, rubygems 3.5.22-7.module+el9.8.0+24406+8975e57f, rubygems 4.0.6-33.module+el9.8.0+24428+77f1d00a, ruby-libs 3.3.10-7.module+el9.8.0+24406+8975e57f, ruby-libs 4.0.3-33.module+el9.8.0+24428+77f1d00a, +40 more
    fixed: vendor fix RHSA-2026:33576
  • Red Hat Enterprise Linux AppStream (v. 10) ruby 3.3.10-13.el10_2, ruby4.0 4.0.3-35.el10_2, rubygems 3.5.22-13.el10_2, ruby-libs 3.3.10-13.el10_2, rubygem-rbs 3.4.0-13.el10_2, rubygem-rss 0.3.1-13.el10_2, +18 more
    fixed: vendor fix RHSA-2026:33565
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) ruby 3.3.10-7.module+el9.4.0+24474+8fc4d0bd, rubygems 3.5.22-7.module+el9.4.0+24474+8fc4d0bd, ruby-libs 3.3.10-7.module+el9.4.0+24474+8fc4d0bd, rubygem-pg 1.5.4-1.module+el9.4.0+21222+faeeed2f, rubygem-rbs 3.4.0-7.module+el9.4.0+24474+8fc4d0bd, rubygem-rss 0.3.1-7.module+el9.4.0+24474+8fc4d0bd, +17 more
    fixed: vendor fix RHSA-2026:36099
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) ruby 3.3.10-11.el10_0.2, rubygems 3.5.22-11.el10_0.2, ruby-libs 3.3.10-11.el10_0.2, rubygem-rbs 3.4.0-11.el10_0.2, rubygem-rss 0.3.1-11.el10_0.2, rubygem-irb 1.13.1-11.el10_0.2, +15 more
    fixed: vendor fix RHSA-2026:35895
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) ruby 3.3.10-6.module+el9.6.0+24475+76cce029, rubygems 3.5.22-6.module+el9.6.0+24475+76cce029, ruby-libs 3.3.10-6.module+el9.6.0+24475+76cce029, rubygem-pg 1.5.4-1.module+el9.4.0+21222+faeeed2f, rubygem-rbs 3.4.0-6.module+el9.6.0+24475+76cce029, rubygem-rss 0.3.1-6.module+el9.6.0+24475+76cce029, +17 more
    fixed: vendor fix RHSA-2026:37238
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) ruby-doc 3.3.10-13.el10_2, ruby4.0-doc 4.0.3-35.el10_2
    fixed: vendor fix RHSA-2026:33565
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) ruby-doc 3.3.10-11.el10_0.2
    fixed: vendor fix RHSA-2026:35895
show 2 more
  • Red Hat Hardened Images ruby3.4 3.4.10-31.hum1, ruby3.4 3.4.8-31.2.hum1, ruby4.0 4.0.0-33.4.hum1, ruby3.3 3.3.10-23.2.hum1, ruby3.4-libs 3.4.10-31.hum1, ruby3.4-libs 3.4.8-31.2.hum1, +78 more
    fixed: vendor fix RHSA-2026:33721
  • Red Hat 3scale API Management Platform 2 3scale-amp21/zync, 3scale-amp22/zync, 3scale-amp21/system, 3scale-amp22/system, 3scale-amp2/zync-rhel8, 3scale-amp2/zync-rhel9, +3 more
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.41% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 2.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
CNA 4.0 2.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:L/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 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
rubygems net-imap
>=0.6.0, <0.6.4
>=0.5.0, <0.5.14
<0.4.24
0.6.4
0.5.14
0.4.24

Affected products

  • ruby net-imap

Classification

Weakness
  • CWE-407 Inefficient Algorithmic Complexity

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.