dbcve.org
FedoraOperating system · Fedoraproject

CVE-2023-38545

CRITICAL · 9.8 CVSS v3.1 Published 2023-10-18
Fix available
A fix is available. Upgrade to 8.4.0 / 10.0.17763.5122 or later.
See remediation →
100/100
Remediation priority · Urgent
High EPSS Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
This flaw makes curl overflow a heap based buffer in the SOCKS5 proxy handshake. When curl is asked to pass along the host name to the SOCKS5 proxy to allow that to resolve the address instead of it getting done by curl itself, the maximum length that host name can be is 255 bytes. If the host name is detected to be longer, curl switches to local name resolving and instead passes on the resolved address only. Due to this bug, the local variable that means "let the host resolve the name" could get the wrong value during a slow SOCKS5 handshake, and contrary to the intention, copy the too long host name to the target buffer instead of copying just the resolved address there. The target buffer being a heap based buffer, and the host name coming from the URL that curl has been told to operate with.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-787

The program writes past the bounds of a buffer, overwriting adjacent memory an attacker can turn to their advantage. Crafted input can overwrite control data and redirect execution. Remediation is validating every index and length before a write, plus modern memory-safety mitigations.

General guidance for the out-of-bounds write class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FedoraOperating system
Affected:= 37
LibcurlApplication
Affected:>= 7.69.0, < 8.4.0
Active Iq Unified ManagerApplication
Affected:all versions
Oncommand InsightApplication
Affected:all versions
Oncommand Workflow AutomationApplication
Affected:all versions
Windows 10 1809Operating system
Affected:< 10.0.17763.5122
Windows 10 21h2Operating system
Affected:< 10.0.19044.3693
Windows 10 22h2Operating system
Affected:< 10.0.19045.3693

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 8.4.0 / 10.0.17763.5122 / 10.0.19044.3693 or later
Fixed in 8.4.010.0.17763.512210.0.19044.3693
Vendor patch curl.se →
Recommended fix High confidence

curl 8.4.0 or later (or distribution-specific security updates that include the CVE-2023-38545 fix)

  1. Identify the installed curl/libcurl version by running 'curl --version' or checking the package manager
  2. For Linux systems using package managers: run 'sudo apt-get update && sudo apt-get upgrade curl' (Debian/Ubuntu) or 'sudo dnf update curl' (Fedora/RHEL)
  3. For macOS: run 'brew upgrade curl' if using Homebrew, or update via system preferences
  4. For Windows: update via Windows Update or download the latest version from https://curl.se/download.html
  5. Verify the fix by running 'curl --version' and confirming the version is 8.4.0 or later
  6. Test that SOCKS5 proxy functionality works correctly with the updated version
Caveat Minimal risk - this is a security patch that fixes a buffer overflow; ensure any SOCKS5 proxy configurations are tested after upgrade

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $3,550. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-38545 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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