HTTP/2 server push UAF
A flaw in libcurl's handling of HTTP/2 Server Push streams, when the parent handle is set to share connections with other handles, can lead to use-after-free in the cleanup process.
- Published
- Sep 6, 2026
- Updated
- Sep 15, 2026
- EPSS
- 0.6% · 46th percentile
- CWE
- CWE-416
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Report tools
Action score
36
Monitor
Low priority for now.
- CVSS
- 36 / 40 · 9.1 / 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 curl7.44.0 and later · before 8.22.0
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
- 8.21.0, 8.20.0, 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 … (+23)affected
- 7.44.0 and later · before 8.14.2affected · semver
- 8.15.0 and later · before 8.16.1affected · semver
- 8.17.0 and later · before 8.20.1affected · semver
- 8.21.0 and later · before 8.22.0affected · semver
- ea7134ac874a66107e54ff93657ac565cf2ec4aa and later · before 90325ff0444cbdff368bda5d26d6405a0bb6ee43affected · 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 7.44.0 · before 8.22.0-r0 | 8.22.0-r0 |
| Debian:12 | curl | all versions | — |
| Debian:14 | curl | before 8.22.0~rc2-1 | 8.22.0~rc2-1 |
| openSUSE:Tumbleweed | curl | before 8.22.0-1.1 | 8.22.0-1.1 |
| Red Hat:hummingbird:1 | cargo | before 0:1.98.0-1.hum1 | 0:1.98.0-1.hum1 |
| Red Hat:hummingbird:1 | clippy | before 0:1.98.0-1.hum1 | 0:1.98.0-1.hum1 |
| Red Hat:hummingbird:1 | curl | before 0:8.22.0-0.1.hum1 | 0:8.22.0-0.1.hum1 |
| Red Hat:hummingbird:1 | libcurl | before 0:8.22.0-0.1.hum1 | 0:8.22.0-0.1.hum1 |
| Red Hat:hummingbird:1 | libcurl-devel | before 0:8.22.0-0.1.hum1 | 0:8.22.0-0.1.hum1 |
| Red Hat:hummingbird:1 | libcurl-minimal | before 0:8.22.0-0.1.hum1 | 0:8.22.0-0.1.hum1 |
| Red Hat:hummingbird:1 | rust | before 0:1.98.0-1.hum1 | 0:1.98.0-1.hum1 |
| Red Hat:hummingbird:1 | rust-analyzer | before 0:1.98.0-1.hum1 | 0:1.98.0-1.hum1 |
| Red Hat:hummingbird:1 | rust-debugger-common | before 0:1.98.0-1.hum1 | 0:1.98.0-1.hum1 |
| Red Hat:hummingbird:1 | rust-doc | before 0:1.98.0-1.hum1 | 0:1.98.0-1.hum1 |
| Red Hat:hummingbird:1 | rust-gdb | before 0:1.98.0-1.hum1 | 0:1.98.0-1.hum1 |
| Red Hat:hummingbird:1 | rust-lldb | before 0:1.98.0-1.hum1 | 0:1.98.0-1.hum1 |
| Red Hat:hummingbird:1 | rust-src | before 0:1.98.0-1.hum1 | 0:1.98.0-1.hum1 |
| Red Hat:hummingbird:1 | rust-std-static | before 0:1.98.0-1.hum1 | 0:1.98.0-1.hum1 |
| Red Hat:hummingbird:1 | rust-std-static-aarch64-unknown-none-softfloat | before 0:1.98.0-1.hum1 | 0:1.98.0-1.hum1 |
| Red Hat:hummingbird:1 | rust-std-static-aarch64-unknown-uefi | before 0:1.98.0-1.hum1 | 0:1.98.0-1.hum1 |
| Red Hat:hummingbird:1 | rust-std-static-i686-pc-windows-gnu | before 0:1.98.0-1.hum1 | 0:1.98.0-1.hum1 |
| Red Hat:hummingbird:1 | rust-std-static-wasm32-unknown-unknown | before 0:1.98.0-1.hum1 | 0:1.98.0-1.hum1 |
| Red Hat:hummingbird:1 | rust-std-static-wasm32-wasip1 | before 0:1.98.0-1.hum1 | 0:1.98.0-1.hum1 |
| Red Hat:hummingbird:1 | rust-std-static-x86_64-pc-windows-gnu | before 0:1.98.0-1.hum1 | 0:1.98.0-1.hum1 |
+3
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 | 8.20.1 | Vendor (CNA) |
| curl curl | 8.22.0 | Vendor (CNA) |
| curl curl | 90325ff0444cbdff368bda5d26d6405a0bb6ee43 | Vendor (CNA) |
| azl3 curl 8.11.1-11 on Azure Linux 3.0 | Release Notes | Microsoft (MSRC) |
| alpine:curl | 8.22.0-r0 · Alpine:v3.23 | Package registry (OSV) |
| debian:curl | 8.22.0~rc2-1 · Debian:14 | Package registry (OSV) |
| opensuse:curl | 8.22.0-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:cargo | 0:1.98.0-1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:clippy | 0:1.98.0-1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:curl | 0:8.22.0-0.1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:libcurl | 0:8.22.0-0.1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:libcurl-devel | 0:8.22.0-0.1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:libcurl-minimal | 0:8.22.0-0.1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:rust | 0:1.98.0-1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:rust-analyzer | 0:1.98.0-1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:rust-debugger-common | 0:1.98.0-1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:rust-doc | 0:1.98.0-1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:rust-gdb | 0:1.98.0-1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:rust-lldb | 0:1.98.0-1.hum1 · Red Hat:hummingbird:1 | 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.
- Daniel Stenbergremediation developer
- Stephan Zeisberg (Security Research Labs)finder
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-1053665 days apartHTTP/2 stream-dependency tree UAF39Monitor
- CVE-2026-802290 days apartOpenSSL provider use-after-free30Monitor
- CVE-2026-3805179 days apartuse after free in SMB connection reuse30Monitor
- CVE-2026-908065 days apartUAF after pause in socket callback29Monitor
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
- none
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-416 · Use After FreeCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
nvd-secondary
Root cause
After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.
The bug in code
The whole CWE-416 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
free(dev->buf);/* ... another thread is still running ... */process(dev->buf);Fixed
lock(&dev->lock);free(dev->buf);dev->buf = NULL;unlock(&dev->lock);Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
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✗ → ✓
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References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.