CVE-2017-12966: The asn1f_lookup_symbol_impl function in asn1fix_retrieve.c in libasn1fix.a in asn1c 0.9.28 allows remote atta

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MEDIUM 6.5DOWNGRADE

CVE-2017-12966 is a medium-severity flaw (CVSS 6.5) affecting asn1c. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The asn1f_lookup_symbol_impl function in asn1fix_retrieve.c in libasn1fix.a in asn1c 0.9.28 allows remote attackers to cause a denial of service (segmentation fault) via a crafted .asn1 file.

Why this priority

Public exploit reference

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

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.1% (top 35%)
CISA exploited list	No
Weakness	CWE-119
Published	2017-08-20
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: asn1c project

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

Am I affected?

Timeline

2017-08-20 16:29 UTCPublished CVE record published
2026-06-17 01:04 UTCUpdated Record last modified

asn1c project asn1c DOWNGRADE

Affected: 0.9.28

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.9.28

1. Check installed version

apt-cache policy asn1c || rpm -q asn1c || asn1c --version

2. No fixed release: DOWNGRADE to a release before 0.9.28 (Debian / Ubuntu)

apt-cache madison asn1c sudo apt install asn1c=<VERSION_BEFORE_0.9.28> sudo apt-mark hold asn1c

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

dnf --showduplicates list asn1c sudo dnf downgrade asn1c-<VERSION_BEFORE_0.9.28> sudo dnf versionlock add asn1c

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-2017-12966?

asn1c: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2017-12966 being exploited?

CVE-2017-12966 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-2017-12966 affect?

CVE-2017-12966 affects asn1c. Severity is medium (CVSS 6.5). The asn1f_lookup_symbol_impl function in asn1fix_retrieve.c in libasn1fix.a in asn1c 0.9.28 allows remote attackers to cause a denial of service (segmentation fault) via a crafted .asn1 file.

How urgent is CVE-2017-12966?

Priority 44/100. Public exploit reference

Related CVEs

CVE-2020-23911 MEDIUM 5.5 UPGRADE An issue was discovered in asn1c through v0.9.28
CVE-2020-23910 MEDIUM 5.5 UPGRADE Stack-based buffer overflow vulnerability in asn1c through v0.9.28 via function genhash_get in genhash.c.
CVE-2016-5080 CRITICAL 9.8 UPGRADE Integer overflow in the rtxMemHeapAlloc function in asn1rt_a.lib in Objective Systems ASN1C for C/C++ before 7

References

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