CVE-2026-5435: The deprecated functions ns_printrrf, ns_printrr and fp_nquery in the GNU C Library version 2.2 and newer fail

Routine

HIGH 7.3REMOTEMITIGATE

CVE-2026-5435 is a high-severity flaw (CVSS 7.3) affecting glibc. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The deprecated functions ns_printrrf, ns_printrr and fp_nquery in the GNU C Library version 2.2 and newer fail to enforce the caller-supplied buffer length, and can result in an out-of-bounds write when printing TSIG records.

Why this priority

High severity
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	7.3 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 85%)
CISA exploited list	No
Weakness	CWE-787
Published	2026-04-28
Last modified	2026-07-14

Publisher (CNA): GNU C Library · Vendor: gnu

Last updated 2026-07-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-28 13:19 UTCPublished CVE record published
2026-07-14 13:19 UTCUpdated Record last modified

gnu glibc MITIGATE

Affected: >= 2.2

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

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

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

Downgrade not recommended

This is a core system component: downgrading can break the OS. Apply the distro update or the vendor mitigation.

Advisories and coverage

Official advisories

AlmaLinux Errata: [ALSA-2026:42952] Moderate: glibc security update 2026-07-23

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-2026-5435?

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

Is CVE-2026-5435 being exploited?

CVE-2026-5435 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-2026-5435 affect?

CVE-2026-5435 affects glibc. Severity is high (CVSS 7.3). The deprecated functions ns_printrrf, ns_printrr and fp_nquery in the GNU C Library version 2.2 and newer fail to enforce the caller-supplied buffer length, and can result in an out-of-bounds write when printing TSIG records.

How urgent is CVE-2026-5435?

Priority 34/100. High severity; Remotely exploitable, no login, no user action

Software pages

glibc vulnerabilities

Related CVEs

CVE-2026-6238 MEDIUM 6.5 MITIGATE The deprecated functions ns_printrrf, ns_printrr and fp_nquery in the GNU C Library version 2.0.1 to version 2
CVE-2026-4438 MEDIUM 5.4 UPGRADE Calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS back
CVE-2026-4437 HIGH 7.5 UPGRADE Calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS back
CVE-2026-4046 HIGH 7.5 UPGRADE The iconv() function in the GNU C Library versions 2.43 and earlier may crash due to an assertion failure when

References

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