CVE-2019-9754: An issue was discovered in Tiny C Compiler (aka TinyCC or TCC) 0.9.27

Routine

MEDIUM 5.5DOWNGRADE

CVE-2019-9754 is a medium-severity flaw (CVSS 5.5) affecting tinycc. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in Tiny C Compiler (aka TinyCC or TCC) 0.9.27. Compiling a crafted source file leads to an 1 byte out of bounds write in the end_macro function in tccpp.c.

Why this priority

Public exploit reference

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

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.9% (top 41%)
CISA exploited list	No
Weakness	CWE-787
Published	2019-03-13
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: tinycc

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

Am I affected?

Timeline

2019-03-13 22:29 UTCPublished CVE record published
2026-06-17 02:44 UTCUpdated Record last modified

tinycc tinycc DOWNGRADE

Affected: 0.9.27

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.9.27

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.9.27 (Debian / Ubuntu)

apt-cache madison tinycc sudo apt install tinycc=<VERSION_BEFORE_0.9.27> sudo apt-mark hold tinycc

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

dnf --showduplicates list tinycc sudo dnf downgrade tinycc-<VERSION_BEFORE_0.9.27> sudo dnf versionlock add tinycc

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-2019-9754?

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

Is CVE-2019-9754 being exploited?

CVE-2019-9754 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-2019-9754 affect?

CVE-2019-9754 affects tinycc. Severity is medium (CVSS 5.5). An issue was discovered in Tiny C Compiler (aka TinyCC or TCC) 0.9.27. Compiling a crafted source file leads to an 1 byte out of bounds write in the end_macro function in tccpp.c.

How urgent is CVE-2019-9754?

Priority 39/100. Public exploit reference

Related CVEs

CVE-2019-12495 MEDIUM 5.5 DOWNGRADE An issue was discovered in Tiny C Compiler (aka TinyCC or TCC) 0.9.27
CVE-2018-20376 MEDIUM 5.5 DOWNGRADE An issue was discovered in Tiny C Compiler (aka TinyCC or TCC) 0.9.27
CVE-2018-20375 MEDIUM 5.5 DOWNGRADE An issue was discovered in Tiny C Compiler (aka TinyCC or TCC) 0.9.27
CVE-2018-20374 MEDIUM 5.5 DOWNGRADE An issue was discovered in Tiny C Compiler (aka TinyCC or TCC) 0.9.27

References

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