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CVE-2026-18924· NVD / CVE Program· CNA curl

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.

CriticalCVSS 9.1 · v3.1—No exploit Fix available
Published
Sep 6, 2026
Updated
Sep 15, 2026
EPSS
0.6% · 46th percentile
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Report tools

JSON

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

VendorProduct
haxxcurl

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.

EcosystemPackageAffected rangeFix
Alpine:v3.23curlfrom 7.44.0 · before 8.22.0-r08.22.0-r0
Debian:12curlall versions—
Debian:14curlbefore 8.22.0~rc2-18.22.0~rc2-1
openSUSE:Tumbleweedcurlbefore 8.22.0-1.18.22.0-1.1
Red Hat:hummingbird:1cargobefore 0:1.98.0-1.hum10:1.98.0-1.hum1
Red Hat:hummingbird:1clippybefore 0:1.98.0-1.hum10:1.98.0-1.hum1
Red Hat:hummingbird:1curlbefore 0:8.22.0-0.1.hum10:8.22.0-0.1.hum1
Red Hat:hummingbird:1libcurlbefore 0:8.22.0-0.1.hum10:8.22.0-0.1.hum1
Red Hat:hummingbird:1libcurl-develbefore 0:8.22.0-0.1.hum10:8.22.0-0.1.hum1
Red Hat:hummingbird:1libcurl-minimalbefore 0:8.22.0-0.1.hum10:8.22.0-0.1.hum1
Red Hat:hummingbird:1rustbefore 0:1.98.0-1.hum10:1.98.0-1.hum1
Red Hat:hummingbird:1rust-analyzerbefore 0:1.98.0-1.hum10:1.98.0-1.hum1
Red Hat:hummingbird:1rust-debugger-commonbefore 0:1.98.0-1.hum10:1.98.0-1.hum1
Red Hat:hummingbird:1rust-docbefore 0:1.98.0-1.hum10:1.98.0-1.hum1
Red Hat:hummingbird:1rust-gdbbefore 0:1.98.0-1.hum10:1.98.0-1.hum1
Red Hat:hummingbird:1rust-lldbbefore 0:1.98.0-1.hum10:1.98.0-1.hum1
Red Hat:hummingbird:1rust-srcbefore 0:1.98.0-1.hum10:1.98.0-1.hum1
Red Hat:hummingbird:1rust-std-staticbefore 0:1.98.0-1.hum10:1.98.0-1.hum1
Red Hat:hummingbird:1rust-std-static-aarch64-unknown-none-softfloatbefore 0:1.98.0-1.hum10:1.98.0-1.hum1
Red Hat:hummingbird:1rust-std-static-aarch64-unknown-uefibefore 0:1.98.0-1.hum10:1.98.0-1.hum1
Red Hat:hummingbird:1rust-std-static-i686-pc-windows-gnubefore 0:1.98.0-1.hum10:1.98.0-1.hum1
Red Hat:hummingbird:1rust-std-static-wasm32-unknown-unknownbefore 0:1.98.0-1.hum10:1.98.0-1.hum1
Red Hat:hummingbird:1rust-std-static-wasm32-wasip1before 0:1.98.0-1.hum10:1.98.0-1.hum1
Red Hat:hummingbird:1rust-std-static-x86_64-pc-windows-gnubefore 0:1.98.0-1.hum10:1.98.0-1.hum1

+3

Same product

haxx: all records

Other 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 t
    50Plan
  • 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-leak
    45Plan
  • 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 app
    42Plan
  • 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 (integer
    42Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
curl curl8.14.2Vendor (CNA)
curl curl8.16.1Vendor (CNA)
curl curl8.20.1Vendor (CNA)
curl curl8.22.0Vendor (CNA)
curl curl90325ff0444cbdff368bda5d26d6405a0bb6ee43Vendor (CNA)
azl3 curl 8.11.1-11 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
alpine:curl8.22.0-r0 · Alpine:v3.23Package registry (OSV)
debian:curl8.22.0~rc2-1 · Debian:14Package registry (OSV)
opensuse:curl8.22.0-1.1 · openSUSE:TumbleweedPackage registry (OSV)
red hat:cargo0:1.98.0-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:clippy0:1.98.0-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:curl0:8.22.0-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:libcurl0:8.22.0-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:libcurl-devel0:8.22.0-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:libcurl-minimal0:8.22.0-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:rust0:1.98.0-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:rust-analyzer0:1.98.0-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:rust-debugger-common0:1.98.0-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:rust-doc0:1.98.0-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:rust-gdb0:1.98.0-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:rust-lldb0:1.98.0-1.hum1 · Red Hat:hummingbird:1Package 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.

EPSS, last 120 days

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.

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

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 UAF
    39Monitor
  • CVE-2026-802290 days apartOpenSSL provider use-after-free
    30Monitor
  • CVE-2026-3805179 days apartuse after free in SMB connection reuse
    30Monitor
  • CVE-2026-908065 days apartUAF after pause in socket callback
    29Monitor

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 Free

CVSS 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.

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

c
free(dev->buf);/* ... another thread is still running ... */process(dev->buf);

Fixed

c
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 help

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records