Medium

CVE-2026-6238 — Buffer overread in ns_printrrf with corrupted RDATA field

The deprecated functions ns_printrrf, ns_printrr and fp_nquery in the GNU C Library version 2.0.1 to version 2.43 fail to validate the RDATA content against the RDATA length in a DNS response when processing A6, CERT, LOC, TKEY or TSIG records, which may allow an attacker to craft a DNS response, causing a target application to crash or read uninitialized memory. These functions are for application debugging only and hence not in the path of code executed by the DNS resolver. Further, they have been deprecated since version 2.34 and should not be used by any new applications. Applications should consider porting away from these interfaces since they may be removed in future versions.

Published Apr 28, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: glibc

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.4% (30-day exploitation probability)+6
Technical severity (medium)+3
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.44%

ahead of 37% of scored CVEs · Oct 15, 2026

Affects

Gnu

Glibc

CVSS base

6.5

Medium · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Gnu Glibc, GNU C Library Glibc).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Gnu	Glibc	≥ 2.2	Vulnerable	NIST National Vulnerability Database
GNU C Library	Glibc	≥ 2.0.1 and ≤ 2.43	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

Low

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
6.5	CVSS 3.1	Medium	3.9	2.5	134c704f-9b21-4f2e-91b3-4a467353bcc0 via NIST National Vulnerability Database
6.5	CVSS 3.1	Medium	—	—	CISA-ADP via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L (score shown at the top: 134c704f-9b21-4f2e-91b3-4a467353bcc0)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-126

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 15, 2026 · 3 reading(s) · max 0.44%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Affected products added · the gnu c library/glibc
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
CVSS changed · 6.5
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Modified
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Apr 28, 2026 · glibc

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

3 on the record

sourceware.org/bugzilla/show_bug.cgi
Issue Tracking, NIST National Vulnerability Database
cert-portal.siemens.com/productcert/html/ssa-082556.html
NIST National Vulnerability Database
inbox.sourceware.org/libc-announce/7a655d55-276f-41fe-b550-feb3ebb2ce91@redhat.com/T/
Third Party Advisory, NIST National Vulnerability Database

Elsewhere on this site

Gnu
every CVE for this vendor

CWE-126
other pages naming this weakness

Related CVEs (same products)

Low CVE-2026-97399 One-byte overread in strncasecmp on Power8 17d
Low CVE-2026-95818 AT_SECURE program buffer overflow via $ORIGIN processing 23d
Medium CVE-2026-86805 AT_SECURE programs may load attacker-controlled code via $ORIGIN 23d
Medium CVE-2026-8674 Assertion failure in the DNS stub resolver with a long search domain 28d
Medium CVE-2026-77117 SHIFT_JISX0213 decoding may hang on crafted input Sep 15, 2026
Medium CVE-2026-80489 EUC_JISX0213 decoding may hang on crafted input Sep 15, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-6238 is "Buffer overread in ns_printrrf with corrupted RDATA field", rated Medium. It affects Glibc (Gnu); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.5 describes technical severity. EPSS 0.44% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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