CVE-2006-0645: Tiny ASN.1 Library (libtasn1) before 0.2.18, as used by (1) GnuTLS 1.2.x before 1.2.10 and 1.3.x before 1.3.4,

This month

HIGH 7.5DOWNGRADE

CVE-2006-0645 is a high-severity flaw (CVSS 7.5) affecting libtasn1. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Tiny ASN.1 Library (libtasn1) before 0.2.18, as used by (1) GnuTLS 1.2.x before 1.2.10 and 1.3.x before 1.3.4, and (2) GNU Shishi, allows attackers to crash the DER decoder and possibly execute arbitrary code via "out-of-bounds access" caused by invalid input, as demonstrated by the ProtoVer SSL test suite.

Why this priority

High severity
EPSS top 10%: very likely to be exploited

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
EPSS exploit chance	3.9% (top 10%)
CISA exploited list	No
Published	2006-02-10
Last modified	2026-06-16

Publisher (CNA): Red Hat, Inc. · Vendor: free software foundation inc.

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2006-02-10 18:06 UTCPublished CVE record published
2026-06-16 22:21 UTCUpdated Record last modified

free software foundation inc. libtasn1 DOWNGRADE

Affected: 0.1.0 · 0.1.1 · 0.1.2 · 0.2.0 · 0.2.1 · 0.2.2 · 0.2.3 · 0.2.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.1.0

1. Check installed version

apt-cache policy libtasn1 || rpm -q libtasn1 || libtasn1 --version

2. No fixed release: DOWNGRADE to a release before 0.1.0 (Debian / Ubuntu)

apt-cache madison libtasn1 sudo apt install libtasn1=<VERSION_BEFORE_0.1.0> sudo apt-mark hold libtasn1

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list libtasn1 sudo dnf downgrade libtasn1-<VERSION_BEFORE_0.1.0> sudo dnf versionlock add libtasn1

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.

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-2006-0645?

libtasn1: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2006-0645 being exploited?

CVE-2006-0645 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-2006-0645 affect?

CVE-2006-0645 affects libtasn1. Severity is high (CVSS 7.5). Tiny ASN.1 Library (libtasn1) before 0.2.18, as used by (1) GnuTLS 1.2.x before 1.2.10 and 1.3.x before 1.3.4, and (2) GNU Shishi, allows attackers to crash the DER decoder and possibly execute arbitrary code via "out-of-bounds access" caus

How urgent is CVE-2006-0645?

Priority 49/100. High severity; EPSS top 10%: very likely to be exploited

Software pages

GnuTLS vulnerabilities

Related CVEs

CVE-2021-46848 CRITICAL 9.1 UPGRADE MITIGATE GNU Libtasn1 before 4.19.0 has an ETYPE_OK off-by-one array size check that affects asn1_encode_simple_der.
CVE-2025-13151 HIGH 7.5 DOWNGRADE Stack-based buffer overflow in libtasn1 version: v4.20.0
CVE-2018-6003 HIGH 7.5 UPGRADE MITIGATE An issue was discovered in the _asn1_decode_simple_ber function in decoding.c in GNU Libtasn1 before 4.13
CVE-2018-1000654 MEDIUM 5.5 DOWNGRADE GNU Libtasn1-4.13 libtasn1-4.13 version libtasn1-4.13, libtasn1-4.12 contains a DoS, specifically CPU usage wi
CVE-2017-6891 HIGH 8.8 DOWNGRADE MITIGATE Two errors in the "asn1_find_node()" function (lib/parser_aux.c) within GnuTLS libtasn1 version 4.10 can be ex

References

← Back to latest CVEs