CurlApplication · Haxx
CVE-2023-23915
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 · uneditedA cleartext transmission of sensitive information vulnerability exists in curl <v7.88.0 that could cause HSTS functionality to behave incorrectly when multiple URLs are requested in parallel. Using its HSTS support, curl can be instructed to use HTTPS instead of using an insecure clear-text HTTP step even when HTTP is provided in the URL. This HSTS mechanism would however surprisingly fail when multiple transfers are done in parallel as the HSTS cache file gets overwritten by the most recentlycompleted transfer. A later HTTP-only transfer to the earlier host name would then *not* get upgraded properly to HSTS.
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 · high confidenceIn curl versions before 7.88.0, the HSTS (HTTP Strict Transport Security) cache file gets overwritten by each completed transfer when multiple URLs are requested in parallel. This causes subsequent HTTP-only transfers to fail HSTS upgrade, potentially resulting in cleartext transmission of sensitive data to hosts that should have been forced to HTTPS.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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
CurlApplication
>= 7.77.0, < 7.88.0all versions= 9.0all versionsall versionsall versionsall versions>= 8.2.0, < 8.2.12>= 9.0.0, < 9.0.6= 9.1.0CVSS 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
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check the installed curl versionRun `curl --version` or examine the curl library version used by the applicationAffected if The version is greater than or equal to 7.77.0 and less than 7.88.0
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Verify if HSTS functionality is enabledLook for HSTS-related curl options such as --hsts flag, HSTS cache file configuration, or CURLOPT_HSTS libcurl option in useAffected if HSTS is enabled and the curl HSTS cache is being utilized
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Identify if parallel transfers are occurringReview application code or configuration that performs multiple concurrent HTTP requests using curlAffected if The application performs multiple parallel HTTP transfers where some would benefit from HSTS upgrades
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Check for affected Splunk Universal Forwarder versionsRun `splunk --version` or check the Splunk UF installationAffected if Splunk UF version is 8.2.0 through 8.2.11, 9.0.0 through 9.0.5, or exactly 9.1.0
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Check for affected NetApp productsVerify the specific NetApp product model and firmware versionAffected if Running NetApp Active IQ Unified Manager any version, Clustered Data Ontap 9.0, or H300s/H500s/H700s/H410s firmware any version
You are affected if you are using curl 7.77.0-7.87.x with HSTS enabled alongside parallel HTTP transfers, or if you are running an affected Splunk Universal Forwarder or NetApp product that embeds the vulnerable curl version.
Generated from the published advisory. Verify against your own configuration.
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 · scoped7.88.08.2.129.0.6
Upgrade curl to version 7.88.0 or later. If immediate upgrade is not possible, avoid using HSTS functionality with parallel transfers until the patch can be applied.
curl 7.88.0 or later
- 1. Identify the current curl version installed (e.g., run: curl --version)
- 2. Upgrade curl to version 7.88.0 or later
- 3. Verify the upgrade was successful by checking the version (curl --version)
- 4. Test HSTS functionality to confirm the vulnerability is remediated
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Curl
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-23915 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2023-23915 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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