cross-proxy Digest auth state leak
Successfully using libcurl to do a transfer over a specific HTTP proxy (`proxyA`) with **Digest** authentication and then changing the proxy host to a second one (`proxyB`) for a second transfer, reusing the same handle, makes libcurl wrongly pass on the `Proxy-Authorization:` header field meant for `proxyA`, to `proxyB`.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; 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 help- Published
- May 13, 2026
- Updated
- Sep 15, 2026
- EPSS
- 0.6% · 46th percentile
- CWE
- CWE-294
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Report tools
Action score
21
Monitor
Low priority for now.
- CVSS
- 21 / 40 · 5.3 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.6%
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 curl7.12.0 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
- 7.12.0 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
- fc6eff13b5414caf6edf22d73a3239e074a04216 and later · before c1cfdf59acbaf9504c4578d4cf56cdd7c8594507affected · 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 7.12.0 · 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 8.20.0-1 | 8.20.0-1 |
| openSUSE:Leap 16.0 | curl | before 8.14.1-160000.9.1 | 8.14.1-160000.9.1 |
| Red Hat:hummingbird:1 | curl | before 0:8.20.0-2.hum1 | 0:8.20.0-2.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 12 SP5-LTSS | curl | before 8.0.1-11.126.1 | 8.0.1-11.126.1 |
| 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 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 | 8.14.2 | Vendor (CNA) |
| curl curl | 8.16.1 | Vendor (CNA) |
| curl curl | 8.20.0 | Vendor (CNA) |
| curl curl | c1cfdf59acbaf9504c4578d4cf56cdd7c8594507 | 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 | 8.14.1-160000.9.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| red hat:curl | 0:8.20.0-2.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.
- Muhamad Arga Reksapatifinder
- 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-2026-1185651 days apartcross-origin Digest auth state leak39Monitor
- CVE-2026-892751 days apartenv-set cross-proxy Digest auth state leak36Monitor
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
- low · data can be read
- Integrity
- none
- Availability
- none
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- Low
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
CWE-294 · Authentication Bypass by Capture-replayCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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)
- Session SidejackingCAPEC-102likelihood: High · High
- KerberoastingCAPEC-509High
- Remote Services with Stolen CredentialsCAPEC-555Very High
- Windows Admin Shares with Stolen CredentialsCAPEC-561
- Reusing Session IDs (aka Session Replay)CAPEC-60likelihood: High · High
- Use of Captured Hashes (Pass The Hash)CAPEC-644likelihood: Medium · High
- Use of Captured Tickets (Pass The Ticket)CAPEC-645likelihood: Low · High
- Use of Known Kerberos CredentialsCAPEC-652likelihood: Medium · High
ATT&CK techniques
- Remote ServicesT1021
- Remote Services:SMB/Windows Admin SharesT1021.002
- Email Collection:Remote Email CollectionT1114.002
- External Remote ServicesT1133
- Access Token Manipulation:Token Impersonation/TheftT1134.001
- Use Alternate Authentication Material:Pass The HashT1550.002
- Use Alternate Authentication Material:Pass The TicketT1550.003
- Use Alternate Authentication Material:Web Session CookieT1550.004
- Adversary-in-the-MiddleT1557
- Steal or Forge Kerberos TicketsT1558
- Steal or Forge Kerberos Tickets:KerberoastingT1558.003
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- curl.se/docs/CVE-2026-7168.html
- curl.se/docs/CVE-2026-7168.json
- www.openwall.com/lists/oss-security/2026/04/29/14
Vendor advisories and official records. Exploit/PoC links are deliberately left out.