CVE-2026-4437: gnu glibc Out-of-bounds Read
CVSS: 7.5v3.1HighModified
AliasesUBUNTU-CVE-2026-4437DEBIAN-CVE-2026-4437CGA-28jr-9938-gm2mCGA-2c26-wc89-p2r5CGA-2f6q-652h-q9m2CGA-2r7g-225x-7g48CGA-2vmx-p942-gvjvCGA-32fx-mwwx-g639CGA-356f-wrgr-x525CGA-35j7-cvwv-8fg3CGA-35w5-57mm-v892CGA-38wp-68ww-w3cmCGA-3c22-mq7g-5h5wCGA-3m36-2gmf-r36gCGA-3ppc-8crm-xcwjCGA-4228-g8r3-w9rgCGA-447g-pcpw-fghrCGA-4883-8mch-5r9wCGA-4885-p2mm-6p65CGA-4cxp-3c8g-wpvvCGA-4rv8-gm3c-8hh4CGA-4x2r-7www-92gwCGA-52cm-fvcp-xxhhCGA-5576-29w2-jwxxCGA-55rw-94jv-88x7CGA-564g-3gcw-p5q2CGA-5cjx-hj36-chv2CGA-5hv8-xmx3-wxhfCGA-5prj-w39w-w5gwCGA-5pxw-5g7g-p9h5CGA-5qgw-c245-3r5wCGA-632x-3xxr-9qjgCGA-6457-r5g7-w72mCGA-68f5-fpgh-h55gCGA-6w68-qpgv-7vh2CGA-776p-pvr6-pjjqCGA-783x-fq6r-cc74CGA-7wrv-wrfh-p8c9CGA-8244-q5r5-438cCGA-8qpr-jg97-m3mfCGA-93f9-3jfr-2xw3CGA-9546-grf7-x5j6CGA-9xfq-4v63-2prpCGA-c9wq-6ffr-r922CGA-cqj5-mpw2-9jcvCGA-f493-mp32-m44pCGA-fj32-8c9f-vxj6CGA-fpxp-wgrw-344vCGA-fqcg-7g7h-vpp4CGA-gf5r-6gwj-m2v9CGA-gf8h-cvqx-2c9gCGA-gj3c-7jjm-w35fCGA-gj4g-6466-f7m3CGA-gxq6-5hqw-4p62CGA-hfqx-mp4r-68q4CGA-hm2f-865v-mqv6CGA-hmv8-gm6g-c272CGA-hr27-935j-887gCGA-hr7j-xc54-wmvqCGA-j4w8-g53q-9p2rCGA-j8hj-fxp5-3hrcCGA-jj27-hh4f-r26fCGA-jq3x-39m7-2hx2CGA-jqw5-j88r-mpm6CGA-mj4m-4f25-f23wCGA-mqg8-9cwf-84pgCGA-mwc8-5vr6-cq52CGA-p4q4-vm9v-wjcwCGA-p62j-pcw3-6m9mCGA-p749-hjhx-g4p5CGA-pcc5-rg3m-rgf4CGA-phpw-4q2f-8pmrCGA-pm9m-w6f6-3vcxCGA-pwx3-6x76-f5pcCGA-q9h5-j3vx-cwrrCGA-qfw8-frvf-4g9vCGA-qgv8-8g95-5gfqCGA-qh3h-3rcp-gqc7CGA-qhfc-j7wv-57rfCGA-qjc4-84cm-3mxjCGA-qp8m-cpw3-9qf6CGA-qp96-7x3h-v76rCGA-qq2w-fg3h-95hxCGA-qvv7-4qrx-v7f8CGA-rg8r-78wf-mfh7CGA-rgc2-m88c-v3g8CGA-rvcq-q5jh-xqxqCGA-rvmr-63g4-4mrjCGA-v372-3hrh-rp79CGA-vcrq-877q-qpp5CGA-vjwm-g34v-cf5gCGA-vmh5-j22p-fmpwCGA-w3pm-2cpg-9w25CGA-w456-9ff3-825wCGA-w4ww-j6cg-2r7fCGA-w7c2-39vr-q86cCGA-wfrp-fgv9-hwhjCGA-wgvw-4g4r-j6q7CGA-wq5x-prm6-fhhxCGA-wxq4-w5gq-4wgmCGA-x24q-hxfj-8vm8CGA-x674-x266-v6gpCGA-x8xr-mxrv-jg24CGA-xc8c-vgvc-6cj8CGA-xjmv-wv33-pfq4CGA-xm54-63h2-p5r6CGA-xq4q-286c-rcpcCGA-xw35-p4f8-598c
Published 20-03-2026Last modified 15-10-2026
Vulnerability summary
CVE-2026-4437 is a high (CVSS 7.5) Out-of-bounds Read vulnerability in gnu glibc. EPSS estimates a 0.34% chance of exploitation in the next 30 days, higher than 25.7% of scored vulnerabilities. 1 public exploit is recorded.
CVSS score
7.5/10
010
High · v3.1 (CVE.org)EPSS score
0.34%
0%100%
Low · +0.01 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits1reference
Advisory lineage
Upstream 0 · Downstream 12 · Related 10Timeline
- 20-03-2026PublishedVulnerability first disclosed.
- 15-10-2026Last modifiedVulnerability information updated.
Description
Calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C Library version 2.34 to version 2.43 could, with a crafted response from the configured DNS server, result in a violation of the DNS specification that causes the application to treat a non-answer section of the DNS response as a valid answer.
CVSS metrics
6 scores · 6 sources · 1 versionHigh 7.5Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HSourcesAll 6 agree
- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · WolfiEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · ChainguardEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- NVDNIST7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.34%
Chance of exploitation in the next 30 days
Percentile
26%
Versus all other CVEs
30-day change
+0.01 pp
From 0.33% on 19-09-2026
19-09-202619-10-2026
EPSS score0.34%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
1 foundExploit Reference (sourceware.org)
Maturity: unknown
Weaknesses
CWE · root causeAffected systems
Chainguard53 products
- glibc< 2.43-r4
- glibc-2.43< 2.43-r4
- glibc-2.43-abi-reportAll versions (No fix recorded)
- glibc-2.43-dev< 2.43-r4
- glibc-2.43-iconv< 2.43-r4
Wolfi53 products
- glibc< 2.43-r4
- glibc-2.43< 2.43-r4
- glibc-2.43-abi-reportAll versions (No fix recorded)
- glibc-2.43-dev< 2.43-r4
- glibc-2.43-iconv< 2.43-r4
Ubuntu2 products
- eglibcAll versions (No fix recorded)
- glibc< 2.39-0ubuntu8.8 | All versions (No fix recorded)
Debian1 product
- glibc< 2.36-9+deb12u14 | < 2.41-12+deb13u3 | < 2.42-14
Gnu1 product
- glibc≥ 2.34, ≤ 2.43
The gnu c library1 product
- glibc≥ 2.34, ≤ 2.43
6 vendors · 111 products
