CVE-2017-6891: Two errors in the "asn1_find_node()" function (lib/parser_aux.c) within GnuTLS libtasn1 version 4.10 can be ex

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HIGH 8.8WATCHLISTDOWNGRADEMITIGATEDOWNGRADE

CVE-2017-6891 is a high-severity flaw (CVSS 8.8) affecting libtasn1, debian linux, bookkeeper. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Two errors in the "asn1_find_node()" function (lib/parser_aux.c) within GnuTLS libtasn1 version 4.10 can be exploited to cause a stacked-based buffer overflow by tricking a user into processing a specially crafted assignments file via the e.g. asn1Coding utility.

Why this priority

High severity
EPSS top 7%: very likely to be exploited
On your watchlist

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

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	5.6% (top 7%)
CISA exploited list	No
Weakness	CWE-787
Published	2017-05-22
Last modified	2026-06-17

Publisher (CNA): Flexera Software LLC · Vendor: apache · debian · gnu

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2017-05-22 19:29 UTCPublished CVE record published
2026-06-17 01:23 UTCUpdated Record last modified

gnu libtasn1 DOWNGRADE

Affected: 4.10

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.10

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 4.10 (Debian / Ubuntu)

apt-cache madison libtasn1 sudo apt install libtasn1=<VERSION_BEFORE_4.10> sudo apt-mark hold libtasn1

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

dnf --showduplicates list libtasn1 sudo dnf downgrade libtasn1-<VERSION_BEFORE_4.10> 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.

debian debian linux MITIGATE

Affected: 8.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

apache bookkeeper DOWNGRADE

Affected: 4.12.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.12.1

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 4.12.1 (Debian / Ubuntu)

apt-cache madison bookkeeper sudo apt install bookkeeper=<VERSION_BEFORE_4.12.1> sudo apt-mark hold bookkeeper

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

dnf --showduplicates list bookkeeper sudo dnf downgrade bookkeeper-<VERSION_BEFORE_4.12.1> sudo dnf versionlock add bookkeeper

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-2017-6891?

libtasn1: downgrade or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation; bookkeeper: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2017-6891 being exploited?

CVE-2017-6891 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-2017-6891 affect?

CVE-2017-6891 affects libtasn1, debian linux, bookkeeper. Severity is high (CVSS 8.8). Two errors in the "asn1_find_node()" function (lib/parser_aux.c) within GnuTLS libtasn1 version 4.10 can be exploited to cause a stacked-based buffer overflow by tricking a user into processing a specially crafted assignments file via the e

How urgent is CVE-2017-6891?

Priority 59/100. High severity; EPSS top 7%: very likely to be exploited; On your watchlist

Software pages

Debian vulnerabilities · GnuTLS vulnerabilities

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References

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