wrong reuse of SMB connection
libcurl might in some circumstances reuse the wrong connection for SMB(S) transfers. libcurl features a pool of recent connections so that subsequent requests can reuse an existing connection to avoid overhead. When reusing a connection a range of criteria must be met. Due to a logical error in the code, a network transfer operation that was requested by an application could wrongfully reuse an existing SMB connection to the same server that was using a different "share" than the new subsequent transfer should. This could in unlucky situations lead to the download of the wrong file or the upload of a file to the wrong place. When this happens, the same credentials are used and the server name is the same.
- Published
- May 13, 2026
- Updated
- Sep 15, 2026
- EPSS
- 0.7% · 49th percentile
- CWE
- CWE-488
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Report tools
Action score
30
Monitor
Low priority for now.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.7%
CISA SSVC decision
- Exploitation
- proof of concept
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
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 curl7.40.0 and later · before 8.20.0
Versions reported by the vendor
Affected version ranges reported by the assigning authority (curl). Independent of NVD's CPE analysis and usually ahead of it.
curl curl
- 8.19.0, 8.18.0, 8.17.0, 8.16.0, 8.15.0, 8.14.1, 8.14.0, 8.13.0, 8.12.1, 8.12.0, 8.11.1, 8.11.0 … (+24)affected
- 7.40.0 and later · before 8.14.2affected · semver
- 8.15.0 and later · before 8.16.1affected · semver
- 8.17.0 and later · before 8.20.0affected · semver
- aec2e865f06669b9cb5d26cc1148d70bc418b163 and later · before 74a169575d6412dc0ff532acdf94de35a6c2a571affected · git
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.23 | curl | from 7.40.0 · before 8.20.0-r0 | 8.20.0-r0 |
| Debian:12 | curl | before 7.88.1-10+deb12u15 | 7.88.1-10+deb12u15 |
| Debian:13 | curl | before 8.14.1-2+deb13u4 | 8.14.1-2+deb13u4 |
| Debian:14 | curl | before 8.20.0~rc2-1 | 8.20.0~rc2-1 |
| openSUSE:Leap 16.0 | curl | before 8.14.1-160000.9.1 | 8.14.1-160000.9.1 |
| openSUSE:Tumbleweed | curl | before 8.20.0-1.1 | 8.20.0-1.1 |
| Red Hat:hummingbird:1 | curl | before 0:8.20.0-0.1.hum1 | 0:8.20.0-0.1.hum1 |
| SUSE:Linux Enterprise Micro 5.3 | curl | before 8.14.1-150400.5.91.1 | 8.14.1-150400.5.91.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP7 | curl | before 8.14.1-150700.7.23.1 | 8.14.1-150700.7.23.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | curl | before 8.14.1-150600.4.51.1 | 8.14.1-150600.4.51.1 |
| SUSE:Linux Enterprise Server 16.0 | curl-mini | before 8.14.1-160000.9.1 | 8.14.1-160000.9.1 |
| SUSE:Linux Enterprise Server LTSS Extended Security 12 SP5 | curl | before 8.0.1-11.123.1 | 8.0.1-11.123.1 |
| SUSE:Linux Micro 6.0 | curl | before 8.14.1-8.1 | 8.14.1-8.1 |
| SUSE:Linux Micro 6.1 | curl | before 8.14.1-slfo.1.1_9.1 | 8.14.1-slfo.1.1_9.1 |
| SUSE:Linux Micro 6.2 | curl | before 8.14.1-160000.9.1 | 8.14.1-160000.9.1 |
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 |
|---|---|---|
| curl curl | 74a169575d6412dc0ff532acdf94de35a6c2a571 | Vendor (CNA) |
| curl curl | 8.14.2 | Vendor (CNA) |
| curl curl | 8.16.1 | Vendor (CNA) |
| curl curl | 8.20.0 | Vendor (CNA) |
| alpine:curl | 8.20.0-r0 · Alpine:v3.23 | Package registry (OSV) |
| debian:curl | 7.88.1-10+deb12u15 · Debian:12 | Package registry (OSV) |
| opensuse:curl | 8.20.0-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:curl | 0:8.20.0-0.1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| suse:curl | 8.14.1-slfo.1.1_9.1 · SUSE:Linux Micro 6.1 | Package registry (OSV) |
| suse:curl-mini | 8.14.1-160000.9.1 · SUSE:Linux Enterprise Server 16.0 | 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.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
- Osama Hamadfinder
- Daniel Stenbergremediation developer
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-19931116 days apartNegotiate ambient user conn reuse39Monitor
- CVE-2026-80231116 days apartnative CA store conn reuse30Monitor
- CVE-2026-845851 days apartwrong reuse for different services26Monitor
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
- high · data can be read
- Integrity
- none
- Availability
- none
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
CWE-488 · Exposure of Data Element to Wrong SessionCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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)
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- curl.se/docs/CVE-2026-5773.html
- curl.se/docs/CVE-2026-5773.json
- www.openwall.com/lists/oss-security/2026/04/29/9
Vendor advisories and official records. Exploit/PoC links are deliberately left out.