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CVE-2026-43823: When initializing an RSA public key from DER or PEM bytes throws an error, the EVP_PKEY* is double-freed: firs

43
This month
HIGH 7.5REMOTEUPGRADE

CVE-2026-43823 is a high-severity flaw (CVSS 7.5) affecting swift-crypto. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

When initializing an RSA public key from DER or PEM bytes throws an error, the EVP_PKEY* is double-freed: first in the catch block, then in the deinit. This can lead to a crash on future memory allocations. This double-free manifests when BoringSSL cannot decode the public key from the bytes provided. This vulnerability is addressed in swift-crypto version 4.5.1.

Why this priority

  • High severity
  • CISA SSVC: public proof of concept
  • Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score7.5 (High)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance0.4% (top 64%)
CISA exploited listNo
WeaknessCWE-415
Published2026-07-23
Last modified2026-10-24
Publisher (CNA): Apple Inc. · Vendor: apple

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

apple swift-crypto UPGRADE
Affected: >= 3.2.0 and <= 4.5.1
Fixed in: newer than 4.5.1
Safe to downgrade to: a release before 3.2.0
1. Check installed version
apt-cache policy swift-crypto || rpm -q swift-crypto || swift-crypto --version
2. UPGRADE to newer than 4.5.1 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade swift-crypto
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade swift-crypto
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 3.2.0 (Debian / Ubuntu)
apt-cache madison swift-crypto sudo apt install swift-crypto=<VERSION_BEFORE_3.2.0> sudo apt-mark hold swift-crypto
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list swift-crypto sudo dnf downgrade swift-crypto-<VERSION_BEFORE_3.2.0> sudo dnf versionlock add swift-crypto
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

Fedora ELN · ntpd-rs · FIXED · 1.7.2-3.eln159 · FEDORA-2026-57e4a99310 · source
sudo dnf upgrade --advisory=FEDORA-2026-57e4a99310
Fedora 46 · moby-engine · FIXED · 29.9.2-2.fc46 · FEDORA-2026-4856be87b3 · source
sudo dnf upgrade --advisory=FEDORA-2026-4856be87b3
Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-2073 · source
sudo dnf update --advisory=ALAS2023-2026-2073

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-43823?

swift-crypto: upgrade to newer than 4.5.1. Exact commands for each OS are on this page.

Is CVE-2026-43823 being exploited?

CVE-2026-43823 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-43823 affect?

CVE-2026-43823 affects swift-crypto. Severity is high (CVSS 7.5). When initializing an RSA public key from DER or PEM bytes throws an error, the EVP_PKEY* is double-freed: first in the catch block, then in the deinit. This can lead to a crash on future memory allocations. This double-free manifests when B

How urgent is CVE-2026-43823?

Priority 43/100. High severity; CISA SSVC: public proof of concept; Remotely exploitable, no login, no user action

References

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