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NVD / CVE Program· CNA mitre

CVE-2020-24606: Squid before 4.13 and 5.x before 5.0.4 allows a trusted peer to perform Denial of Service by consuming all available CPU cycles during…

HighCVSS 7.5 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 31/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 4.6% (FIRST EPSS); higher than 91.7% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: libecap (AlmaLinux:8) 1.0.1-2.module_el8.6.0+2741+01592ae8; libecap-devel (AlmaLinux:8) 1.0.1-2.module_el8.6.0+2741+01592ae8; squid (Alpine:v3.10) 4.13-r0.
  • Mentioned 2 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to libecap (AlmaLinux:8) 1.0.1-2.module_el8.6.0+2741+01592ae8; libecap-devel (AlmaLinux:8) 1.0.1-2.module_el8.6.0+2741+01592ae8; squid (Alpine:v3.10) 4.13-r0 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Squid before 4.13 and 5.x before 5.0.4 allows a trusted peer to perform Denial of Service by consuming all available CPU cycles during handling of a crafted Cache Digest response message. This only occurs when cache_peer is used with the cache digests feature. The problem exists because peerDigestHandleReply() livelocking in peer_digest.cc mishandles EOF.

Published
Aug 24, 2020
Updated
Jun 16, 2026
EPSS
4.6% · 91th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 4.6%

CNA vs NVD score

NVD
7.5
CNA · mitre
8.6
1.1 point gap

CVSS:3.1/AC:L/AV:N/A:H/C:N/I:N/PR:N/S:C/UI:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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  • when exploit code appears or is weaponized
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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
squid-cachesquid
canonicalubuntu linux
debiandebian linux
fedoraprojectfedora
opensuseleap

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • canonical ubuntu linux16.04
  • canonical ubuntu linux18.04
  • canonical ubuntu linux20.04
  • debian debian linux10.0
  • debian debian linux9.0
  • fedoraproject fedora31
  • fedoraproject fedora32
  • fedoraproject fedora33
+4 more rows
  • opensuse leap15.1
  • opensuse leap15.2
  • squid-cache squid5.0.1 and later · before 5.0.4
  • squid-cache squid3.0 and later · before 4.13

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:8libecapbefore 1.0.1-2.module_el8.6.0+2741+01592ae81.0.1-2.module_el8.6.0+2741+01592ae8
AlmaLinux:8libecap-develbefore 1.0.1-2.module_el8.6.0+2741+01592ae81.0.1-2.module_el8.6.0+2741+01592ae8
Alpine:v3.10squidfrom 3.0 · before 4.13-r04.13-r0
Alpine:v3.13squidfrom 3.0 · before 4.13.0-r04.13.0-r0
Debian:10squidbefore 4.6-1+deb10u44.6-1+deb10u4
Debian:12squidbefore 4.13-14.13-1
Debian:9squid3before 3.5.23-5+deb9u53.5.23-5+deb9u5
openSUSE:Leap 15.1squidbefore 4.13-lp151.2.24.14.13-lp151.2.24.1
openSUSE:Leap 15.2squidbefore 4.13-lp152.2.6.14.13-lp152.2.6.1
Red Hat:enterprise_linux:7::serversquidbefore 7:3.5.20-17.el7_9.47:3.5.20-17.el7_9.4
Red Hat:enterprise_linux:7::serversquid-debuginfobefore 7:3.5.20-17.el7_9.47:3.5.20-17.el7_9.4
Red Hat:enterprise_linux:7::serversquid-migration-scriptbefore 7:3.5.20-17.el7_9.47:3.5.20-17.el7_9.4
Red Hat:enterprise_linux:7::serversquid-sysvinitbefore 7:3.5.20-17.el7_9.47:3.5.20-17.el7_9.4
Red Hat:enterprise_linux:8::appstreamlibecapbefore 0:1.0.1-2.module+el8.1.0+4044+36416a770:1.0.1-2.module+el8.1.0+4044+36416a77
Red Hat:enterprise_linux:8::appstreamlibecap-debuginfobefore 0:1.0.1-2.module+el8.1.0+4044+36416a770:1.0.1-2.module+el8.1.0+4044+36416a77
Red Hat:enterprise_linux:8::appstreamlibecap-debugsourcebefore 0:1.0.1-2.module+el8.1.0+4044+36416a770:1.0.1-2.module+el8.1.0+4044+36416a77
Red Hat:enterprise_linux:8::appstreamlibecap-develbefore 0:1.0.1-2.module+el8.1.0+4044+36416a770:1.0.1-2.module+el8.1.0+4044+36416a77
Red Hat:enterprise_linux:8::appstreamsquidbefore 7:4.11-3.module+el8.3.0+7851+7808b5f97:4.11-3.module+el8.3.0+7851+7808b5f9
Red Hat:enterprise_linux:8::appstreamsquid-debuginfobefore 7:4.11-3.module+el8.3.0+7851+7808b5f97:4.11-3.module+el8.3.0+7851+7808b5f9
Red Hat:enterprise_linux:8::appstreamsquid-debugsourcebefore 7:4.11-3.module+el8.3.0+7851+7808b5f97:4.11-3.module+el8.3.0+7851+7808b5f9
Rocky Linux:8libecapbefore 0:1.0.1-2.module+el8.4.0+404+316a0dc50:1.0.1-2.module+el8.4.0+404+316a0dc5
SUSE:HPE Helion OpenStack 8squidbefore 3.5.21-26.32.13.5.21-26.32.1
SUSE:Linux Enterprise Module for Server Applications 15 SP1squidbefore 4.13-5.23.14.13-5.23.1
SUSE:Linux Enterprise Point of Sale 11 SP3squid3before 3.1.23-8.16.37.15.13.1.23-8.16.37.15.1

+1

Same product

squid-cache: all records

Other highest-scoring records for the same primary product.

  • CVE-2024-25617Denial of Service in HTTP Header parser in squid proxy
    56Plan
  • CVE-2023-49285Denial of Service in HTTP Message Processing in Squid
    56Plan
  • CVE-2021-31806An issue was discovered in Squid before 4.15 and 5.x before 5.0.6.
    55Plan

Published before and after this one in the same product

  • ← EarlierCVE-2020-14058Jun 30, 2020 · An issue was discovered in Squid before 4.12 and 5.x before 5.0.3.
    31Monitor
  • ← EarlierCVE-2020-14059Jun 30, 2020 · An issue was discovered in Squid 5.x before 5.0.3.
    27Monitor
  • Later →CVE-2020-15810Sep 2, 2020 · An issue was discovered in Squid before 4.13 and 5.x before 5.0.4.
    27Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
almalinux:libecap1.0.1-2.module_el8.6.0+2741+01592ae8 · AlmaLinux:8Package registry (OSV)
almalinux:libecap-devel1.0.1-2.module_el8.6.0+2741+01592ae8 · AlmaLinux:8Package registry (OSV)
alpine:squid4.13-r0 · Alpine:v3.10Package registry (OSV)
debian:squid4.13-1 · Debian:12Package registry (OSV)
debian:squid33.5.23-5+deb9u5 · Debian:9Package registry (OSV)
opensuse:squid4.13-lp151.2.24.1 · openSUSE:Leap 15.1Package registry (OSV)
red hat:libecap0:1.0.1-2.module+el8.1.0+4044+36416a77 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:libecap-debuginfo0:1.0.1-2.module+el8.1.0+4044+36416a77 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:libecap-debugsource0:1.0.1-2.module+el8.1.0+4044+36416a77 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:libecap-devel0:1.0.1-2.module+el8.1.0+4044+36416a77 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:squid7:3.5.20-17.el7_9.4 · Red Hat:enterprise_linux:7::serverPackage registry (OSV)
red hat:squid-debuginfo7:3.5.20-17.el7_9.4 · Red Hat:enterprise_linux:7::serverPackage registry (OSV)
red hat:squid-debugsource7:4.11-3.module+el8.3.0+7851+7808b5f9 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:squid-migration-script7:3.5.20-17.el7_9.4 · Red Hat:enterprise_linux:7::serverPackage registry (OSV)
red hat:squid-sysvinit7:3.5.20-17.el7_9.4 · Red Hat:enterprise_linux:7::serverPackage registry (OSV)
rocky linux:libecap0:1.0.1-2.module+el8.4.0+404+316a0dc5 · Rocky Linux:8Package registry (OSV)
suse:squid4.13-5.23.1 · SUSE:Linux Enterprise Module for Server Applications 15 SP1Package registry (OSV)
suse:squid33.1.23-8.16.37.15.1 · SUSE:Linux Enterprise Point of Sale 11 SP3Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Not on record for this CVE: EPSS history · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-667 · Improper Locking

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

References

Show all references (13 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records