CVE-2019-1543: ChaCha20-Poly1305 is an AEAD cipher, and requires a unique nonce input for every encryption operation

Q: How do I fix CVE-2019-1543?

openssl: upgrade to newer than 1.1.1b. Exact commands for each OS are on this page.

Q: Is CVE-2019-1543 being exploited?

CVE-2019-1543 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2019-1543 affect?

CVE-2019-1543 affects openssl. Severity is high (CVSS 7.4). ChaCha20-Poly1305 is an AEAD cipher, and requires a unique nonce input for every encryption operation. RFC 7539 specifies that the nonce value (IV) should be 96 bits (12 bytes). OpenSSL allows a variable nonce length and front pads the nonc

Q: How urgent is CVE-2019-1543?

Priority 59/100. High severity; EPSS top 7%: very likely to be exploited; Remotely exploitable, no login, no user action; On your watchlist

This month

HIGH 7.4REMOTEWATCHLISTUPGRADE

CVE-2019-1543 is a high-severity flaw (CVSS 7.4) affecting openssl. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

ChaCha20-Poly1305 is an AEAD cipher, and requires a unique nonce input for every encryption operation. RFC 7539 specifies that the nonce value (IV) should be 96 bits (12 bytes). OpenSSL allows a variable nonce length and front pads the nonce with 0 bytes if it is less than 12 bytes. However it also incorrectly allows a nonce to be set of up to 16 bytes. In this case only the last 12 bytes are significant and any additional leading bytes are ignor

Why this priority

High severity
EPSS top 7%: very likely to be exploited
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.4 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	5.7% (top 7%)
CISA exploited list	No
Weakness	CWE-327, CWE-330
Published	2019-03-06
Last modified	2026-11-02

Publisher (CNA): OpenSSL Software Foundation · Vendor: openssl

Last updated 2026-11-02 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2019-03-06 21:29 UTCPublished CVE record published
2026-11-02 18:18 UTCUpdated Record last modified

openssl openssl UPGRADE

Affected: >= 1.1.0 and <= 1.1.0j · >= 1.1.1 and <= 1.1.1b

Fixed in: newer than 1.1.1b

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy openssl || rpm -q openssl || openssl --version

2. UPGRADE to newer than 1.1.1b (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade openssl

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade openssl

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2019-1543?

openssl: upgrade to newer than 1.1.1b. Exact commands for each OS are on this page.

Is CVE-2019-1543 being exploited?

CVE-2019-1543 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-2019-1543 affect?

CVE-2019-1543 affects openssl. Severity is high (CVSS 7.4). ChaCha20-Poly1305 is an AEAD cipher, and requires a unique nonce input for every encryption operation. RFC 7539 specifies that the nonce value (IV) should be 96 bits (12 bytes). OpenSSL allows a variable nonce length and front pads the nonc

How urgent is CVE-2019-1543?

Priority 59/100. High severity; EPSS top 7%: very likely to be exploited; Remotely exploitable, no login, no user action; On your watchlist

Software pages

OpenSSL vulnerabilities

Related CVEs

CVE-2019-1552 LOW 3.3 UPGRADE OpenSSL has internal defaults for a directory tree where it can find a configuration file as well as certifica
CVE-2006-4339 CRITICAL 9.1 UPGRADE A flaw was found in OpenSSL
CVE-2018-0737 MEDIUM 5.9 UPGRADE MITIGATE The OpenSSL RSA Key generation algorithm has been shown to be vulnerable to a cache timing side channel attack
CVE-2025-15467 HIGH 8.8 UPGRADE Issue summary: Parsing CMS AuthEnvelopedData or EnvelopedData message with maliciously crafted AEAD parameters
CVE-2024-0727 MEDIUM 5.5 UPGRADE Issue summary: Processing a maliciously formatted PKCS12 file may lead OpenSSL to crash leading to a potential

References

← Back to latest CVEs