The (1) mbed_connect_step1 function in lib/vtls/mbedtls.c and (2) polarssl_connect_step1 function in lib/vtls/polarssl.c in cURL and libcurl
The (1) mbed_connect_step1 function in lib/vtls/mbedtls.c and (2) polarssl_connect_step1 function in lib/vtls/polarssl.c in cURL and libcurl before 7.49.0, when using SSLv3 or making a TLS connection to a URL that uses a numerical IP address, allow remote attackers to spoof servers via an arbitrary valid certificate.
Noroxi analysis
No Noroxi analysis for this record yet
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We use this product, ask for help- Published
- May 20, 2016
- Updated
- Jun 16, 2026
- EPSS
- 6.9% · 94th percentile
- CWE
- CWE-20
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Report tools
Action score
23
Monitor
Low priority for now.
- CVSS
- 21 / 40 · 5.3 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 2 / 30 · 6.9%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| haxx | curl | cpe:2.3:a:haxx:curl |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- haxx curl7.21.0
- haxx curl7.21.1
- haxx curl7.21.2
- haxx curl7.21.3
- haxx curl7.21.4
- haxx curl7.21.5
- haxx curl7.21.6
- haxx curl7.21.7
- haxx curl7.22.0
- haxx curl7.23.0
- haxx curl7.23.1
- haxx curl7.24.0
- haxx curl7.25.0
- haxx curl7.26.0
- haxx curl7.27.0
- haxx curl7.28.0
- haxx curl7.28.1
- haxx curl7.29.0
- haxx curl7.30.0
- haxx curl7.31.0
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | curl | before 7.50.1-1 | 7.50.1-1 |
Same product
haxx: all recordsOther highest-scoring records for the same primary product.
- CVE-2021-22901curl 7.75.0 through 7.76.1 suffers from a use-after-free vulnerability resulting in already freed memory being used when a TLS 1.3 session t50Plan
- CVE-2023-38039When curl retrieves an HTTP response, it stores the incoming headers so that
they can be accessed later via the libcurl headers API.47Plan
- CVE-2024-2398HTTP/2 push headers memory-leak45Plan
- CVE-2019-5482Heap buffer overflow in the TFTP protocol handler in cURL 7.19.4 to 7.65.3.44Plan
- CVE-2017-8817The FTP wildcard function in curl and libcurl before 7.57.0 allows remote attackers to cause a denial of service (out-of-bounds read and app42Plan
- CVE-2017-8816The NTLM authentication feature in curl and libcurl before 7.57.0 on 32-bit platforms allows attackers to cause a denial of service (integer42Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:curl | 7.50.1-1 · Debian:12 | Package 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.
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 researchersFinders, 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.
- A user must open a link or visit a page.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- none
- Integrity
- high · data or configuration can be modified
- Availability
- none
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- High
- Availability impact
- None
Weakness class (CWE)
CWE-20 · Improper Input ValidationCVSS vector
CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
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.
Attack patterns (CAPEC)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Server Side Include (SSI) InjectionCAPEC-101likelihood: High · High
- Cross Zone ScriptingCAPEC-104likelihood: Medium · High
- Command Line Execution through SQL InjectionCAPEC-108likelihood: Low · Very High
- Object Relational Mapping InjectionCAPEC-109likelihood: Low · High
- SQL Injection through SOAP Parameter TamperingCAPEC-110likelihood: High · Very High
- Double EncodingCAPEC-120likelihood: Low · Medium
- Subverting Environment Variable ValuesCAPEC-13likelihood: High · Very High
ATT&CK techniques
- Obfuscated Files or InformationT1027
- Masquerading: Invalid Code SignatureT1036.001
- Steal Web Session CookieT1539
- Subvert Trust Controls: Code SigningT1553.002
- Impair Defenses:Impair Command History LoggingT1562.003
- Hijack Execution Flow:Dynamic Linker HijackingT1574.006
- Hijack Execution Flow:Path Interception by PATH Environment VariableT1574.007
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- www.openwall.com/lists/oss-security/2024/03/27/4
- www.oracle.com/technetwork/security-advisory/cpuoct2018-4428296.html
- www.securityfocus.com/bid/90726
- www.securitytracker.com/id/1035907
- www.slackware.com/security/viewer.php?l=slackware-security&y=2016&m=slackware-security.495349
- curl.haxx.se/CVE-2016-3739.patch
- curl.haxx.se/changes.html#7_49_0
- curl.haxx.se/docs/adv_20160518.html
- h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05320149
- h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05390722
- security.gentoo.org/glsa/201701-47
Vendor advisories and official records. Exploit/PoC links are deliberately left out.