Skip to content
Noroxi
NVD / CVE Program· CNA mitre

CVE-2019-18676: An issue was discovered in Squid 3.x and 4.x through 4.8.

Noroxi assessment

Priority: Monitor (action score 33/100)

  • 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: 9.1% (FIRST EPSS); higher than 95.3% 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 (Debian:10) 4.6-1+deb10u2.

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 (Debian:10) 4.6-1+deb10u2 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

An issue was discovered in Squid 3.x and 4.x through 4.8. Due to incorrect input validation, there is a heap-based buffer overflow that can result in Denial of Service to all clients using the proxy. Severity is high due to this vulnerability occurring before normal security checks; any remote client that can reach the proxy port can trivially perform the attack via a crafted URI scheme.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Nov 26, 2019
Updated
Jun 16, 2026
EPSS
9.1% · 95th percentile

Report tools

JSON

Action score

33

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
3 / 30 · 9.1%

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

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2019-18676

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits instantly.

Your free account also gets you

Running WordPress? Scan your site free with WP Lens

  • Stack alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for squid-cache records

Running WordPress? Scan your site free with WP Lens

Is your version affected? Check it

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.

We use this product, ask for help

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
fedoraprojectfedora
debiandebian linux

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 linux19.04
  • canonical ubuntu linux19.10
  • debian debian linux10.0
  • debian debian linux9.0
  • fedoraproject fedora30
  • fedoraproject fedora31
  • squid-cache squid4.0 and later · up to 4.8 inclusive
  • squid-cache squid3.0 and later · up to 3.5.28 inclusive

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
Debian:10squidbefore 4.6-1+deb10u24.6-1+deb10u2
Debian:12squidbefore 4.9-14.9-1
Debian:9squid3before 3.5.23-5+deb9u23.5.23-5+deb9u2
openSUSE:Leap 15.0squidbefore 4.9-lp150.13.14.9-lp150.13.1
openSUSE:Leap 15.1squidbefore 4.9-lp151.2.7.14.9-lp151.2.7.1
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 3.5.21-26.20.13.5.21-26.20.1
SUSE:Linux Enterprise Module for Server Applications 15squidbefore 4.9-5.11.14.9-5.11.1
SUSE:Linux Enterprise Point of Sale 11 SP3squidbefore 2.7.STABLE5-2.12.30.6.12.7.STABLE5-2.12.30.6.1
SUSE:Linux Enterprise Point of Sale 11 SP3squid3before 3.1.23-8.16.37.12.13.1.23-8.16.37.12.1
SUSE:Linux Enterprise Server 12 SP5squidbefore 4.9-4.3.24.9-4.3.2

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-2019-12523Nov 26, 2019 · An issue was discovered in Squid before 4.9.
    37Monitor
  • ← EarlierCVE-2019-12526Nov 26, 2019 · An issue was discovered in Squid before 4.9.
    45Plan
  • Later →CVE-2019-18677Nov 26, 2019 · An issue was discovered in Squid 3.x and 4.x through 4.8 when the append_domain setting is used (because the appended characters do not prop
    26Monitor

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)
debian:squid4.9-1 · Debian:12Package registry (OSV)
debian:squid33.5.23-5+deb9u2 · Debian:9Package registry (OSV)
opensuse:squid4.9-lp150.13.1 · openSUSE:Leap 15.0Package 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:squid7:4.11-3.module+el8.3.0+7851+7808b5f9 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:squid-debuginfo7:4.11-3.module+el8.3.0+7851+7808b5f9 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:squid-debugsource7:4.11-3.module+el8.3.0+7851+7808b5f9 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
rocky linux:libecap0:1.0.1-2.module+el8.4.0+404+316a0dc5 · Rocky Linux:8Package registry (OSV)
suse:squid4.9-5.11.1 · SUSE:Linux Enterprise Module for Server Applications 15Package registry (OSV)
suse:squid33.1.23-8.16.37.12.1 · 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.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

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

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

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-787 · Out-of-bounds Write

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.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (9 more)

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

All records