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Fencer Intel
high 8.1

CVE-2026-87863 json

HSTS response erases persisted entries

published 22d ago modified 12d ago also EUVD-2026-105311

cvss
8.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 57%
public exploits
0
none known

Summary

An authenticated HTTPS origin can supply an HSTS `max-age` value that the parser accepts, but time serialization later fails to process. On 64-bit systems, extreme max-age values compute an absolute expiry within standard time integer limits that exceeds calendar time structure bounds. During cache saves, the original HSTS file is truncated before writing a temporary replacement; when serialization fails, the temporary file is deleted, leaving an empty or partial cache. Because the save error is silently ignored during cleanup, curl exits successfully despite the data loss.

Patch / fix

  • haxx curl 8.14.3, 8.16.2, 8.20.2, 8.23.0
  • curl Ubuntu 24.04 LTS 8.5.0-2ubuntu10.16
  • curl Ubuntu 26.10 8.20.0-2ubuntu11.1
  • curl Ubuntu 26.04 LTS 8.18.0-1ubuntu2.8

ubuntu advisories UBUNTU-CVE-2026-87863

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • curl hummingbird 1 8.23.0-0.1.hum1
  • libcurl hummingbird 1 8.23.0-0.1.hum1
  • libcurl-minimal hummingbird 1 8.23.0-0.1.hum1

red hat advisories RHSA-2026:82895

  • curl SLE Module for Basesystem 15 SP7 8.22.0-150700.7.33.1
  • curl SLES 15 SP5-LTSS, SLES 15 SP4-LTSS, SLE Micro 5.5 +8 more 8.14.1-150400.5.98.1
  • curl SLES for SAP 15 SP6, SLES 15 SP6-LTSS 8.22.0-150600.4.58.1

suse advisories SUSE-SU-2026:5069-1SUSE-SU-2026:5068-1SUSE-SU-2026:4954-1

  • curl openSUSE Tumbleweed 8.23.0-1.1

opensuse advisories openSUSE-SU-2026:12150-1

  • curl Alpine 3.24, Alpine 3.23 8.23.0-r0

alpine advisories ALPINE-CVE-2026-87863

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2026-87863 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-87863 updated cvss 3.7

curl: curl: Hsts Response Erases Persisted Entries

  • Red Hat Enterprise Linux 9 snphost Red Hat Enterprise Linux 10 curl, snphost Red Hat JBoss Core Services jbcs-httpd24-curl, jbcs-httpd24-libcurl Red Hat Satellite 6 puppet-agent, openvox-agent
    affected: no fix available “Fix deferred”
  • Red Hat Hardened Images curl 8.23.0-0.1.hum1, libcurl 8.23.0-0.1.hum1, libcurl-minimal 8.23.0-0.1.hum1
    fixed: vendor fix RHSA-2026:82895
  • Red Hat Enterprise Linux 6 curl, libcurl Red Hat Enterprise Linux 7 curl, libcurl Red Hat Enterprise Linux 8 curl, libcurl, libcurl-minimal Red Hat Enterprise Linux 9 curl, rust, cargo, clippy, libcurl, rustfmt, +12 more Red Hat Enterprise Linux 10 igvm, rust, trustee, s390utils Red Hat Hardened Images rust
    +1 more products
    Red Hat Satellite 6 foreman, foreman-cli, foreman-ec2, foreman-gce, foreman-ovirt, foreman-vmware, +9 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
12d ago

Exploit prediction

0.83% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • hackerone.com https://hackerone.com/reports/3972373 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 8.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 8.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • curl curl

Classification

Weakness
  • CWE-201 Insertion of Sensitive Information Into Sent Data

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.