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Vulnerabilities

Security fix · CVE-2019-1543

ChaCha20-Poly1305 is an AEAD cipher, and requires a unique nonce input for every encryption operation.

Published Mar 6, 2019 · catalog updated Nov 2, 2026 · ChaCha20-Poly1305 is an AEAD

Last checked Nov 5, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2019-1543. EPSS is 5.70%. Act only if a listed version of ChaCha20-Poly1305 is an AEAD is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (ChaCha20-Poly1305 is an AEAD).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High7.4
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
5.70%
Remediation
Version ranges on file
Affected products
cpe openssl/openssl

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 ignored. It is a requirement of using this cipher that nonce values are unique. Messages encrypted using a reused nonce value are susceptible to serious confidentiality and integrity attacks. If an application changes the default nonce length to be longer than 12 bytes and then makes a change to the leading bytes of the nonce expecting the new value to be a new unique nonce then such an application could inadvertently encrypt messages with a reused nonce. Additionally the ignored bytes in a long nonce are not covered by the integrity guarantee of this cipher. Any application that relies on the integrity of these ignored leading bytes of a long nonce may be further affected. Any OpenSSL internal use of this cipher, including in SSL/TLS, is safe because no such use sets such a long nonce value. However user applications that use this cipher directly and set a non-default nonce length to be longer than 12 bytes may be vulnerable. OpenSSL versions 1.1.1 and 1.1.0 are affected by this issue. Due to the limited scope of affected deployments this has been assessed as low severity and therefore we are not creating new releases at this time. Fixed in OpenSSL 1.1.1c (Affected 1.1.1-1.1.1b). Fixed in OpenSSL 1.1.0k (Affected 1.1.0-1.1.0j).

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe openssl/openssl>= 1.1.0, <= 1.1.0j
  • cpe openssl/openssl>= 1.1.1, <= 1.1.1b

How to fix CVE-2019-1543

  • Upgrade

    CVE-2019-1543 lists a fix boundary at 1.1.0j. Compare the installed build with that boundary before you change production.

  • Version check

    Affected <= 1.1.0j

  • Advisory

    Open the cve_org record and follow its fix.

  • Official advisories

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2019-1543. EPSS is 5.70%. Act only if a listed version of ChaCha20-Poly1305 is an AEAD is installed.

Which versions are affected?

Compare what you have installed with >= 1.1.0, <= 1.1.0j, >= 1.1.1, <= 1.1.1b. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-327: Use of a Broken or Risky Cryptographic Algorithm; CWE-330: Insufficiently Random Values. EPSS 5.70%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

OpenSSL security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 6, 2019 · NIST NVD

    Detected

    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 sign

  2. Nov 2, 2026 · NIST NVD

    Updated

    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 sign

Sources

  • CVE.orgVulnerability recordCVE-2019-1543

    Official CVE identifier

    cve.org
  • NIST NVDVulnerability recordCVE-2019-1543

    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 byt

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 5, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CVE.orgNov 4, 2026
  • NIST NVDNov 2, 2026