CVE-2026-27651: f5 nginx open source NULL Pointer Dereference
CVSS: 8.7v4.0HighModified
AliasesALPINE-CVE-2026-27651UBUNTU-CVE-2026-27651DEBIAN-CVE-2026-27651CGA-5hv9-mh2w-75gfCGA-9pqw-5rjc-mg3cCGA-m8rw-wpwc-8qxcCGA-pqf9-8r59-26xh
Published 24-03-2026Last modified 15-07-2026
Vulnerability summary
CVE-2026-27651 is a high (CVSS 8.7) NULL Pointer Dereference vulnerability in f5 nginx open source. EPSS estimates a 1.68% chance of exploitation in the next 30 days, higher than 76.5% of scored vulnerabilities.
CVSS score
8.7/10
010
High · v4.0 (CVE.org)EPSS score
1.68%
0%100%
Low · +0.74 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 17 · Related 5MGASA-2026-0111OPENSUSE-SU-2026:10423-1RHSA-2026:13634RHSA-2026:13680RHSA-2026:13839RHSA-2026:14836RHSA-2026:15942RHSA-2026:15943RHSA-2026:15945RHSA-2026:15966RHSA-2026:6906RHSA-2026:6907RHSA-2026:6923RHSA-2026:7002RHSA-2026:7343RHSA-2026:8346SUSE-SU-2026:2370-1CGA-756H-37XJ-VP8MUSN-8210-1USN-8375-1
Timeline
- 24-03-2026PublishedVulnerability first disclosed.
- 15-07-2026Last modifiedVulnerability information updated.
Description
When the ngx_mail_auth_http_module module is enabled on NGINX Plus or NGINX Open Source, undisclosed requests can cause worker processes to terminate. This issue may occur when (1) CRAM-MD5 or APOP authentication is enabled, and (2) the authentication server permits retry by returning the Auth-Wait response header. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
CVSS metrics
10 scores · 7 sources · 2 versionsHigh 8.7Preferred score · CVE.org (CNA)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NSourcesAll 7 agree
- OSV · AlpineEcosystem advisory · calculated8.7HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- OSV · UbuntuEcosystem advisory · calculated8.7HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- OSV · DebianEcosystem advisory · calculated8.7HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- OSV · WolfiEcosystem advisory · calculated8.7HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- OSV · ChainguardEcosystem advisory · calculated8.7HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- NVDNIST8.7HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
High 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 3 agree
- OSV · UbuntuEcosystem 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
1.68%
Chance of exploitation in the next 30 days
Percentile
77%
Versus all other CVEs
30-day change
+0.74 pp
From 0.94% on 19-09-2026
19-09-202619-10-2026
EPSS score1.68%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Chainguard2 products
- nginx-mainline< 1.29.7-r0
- nginx-stable< 1.28.3-r0
F52 products
- nginx open source≥ 0.5.15, < 1.28.3 | ≥ 0.5.15, ≤ 0.9.7 | ≥ 1.0.0, < 1.28.3 | ≥ 1.29.0, < 1.29.7
- nginx plus≥ R36, < R36 P3 | ≥ R35, < R35 P2 | ≥ R34 (No fix recorded) | ≥ R33 (No fix recorded) | ≥ R32, < R32 P5 | ≥ r33, < r35 | r32 | r32:p1 | r32:p2 | r32:p3 | r32:p4 | r35 | r35:p1 | r36 | r36:p1 | r36:p2
Wolfi2 products
- nginx-mainline< 1.29.7-r0
- nginx-stable< 1.28.3-r0
Alpine1 product
- nginx< 1.28.3-r0
Debian1 product
- nginx< 1.22.1-9+deb12u5 | < 1.26.3-3+deb13u3 | < 1.28.3-1
Ubuntu1 product
- nginx< 1.4.6-1ubuntu3.9+esm6 | < 1.10.3-0ubuntu0.16.04.5+esm7 | < 1.14.0-0ubuntu1.11+esm2 | < 1.18.0-0ubuntu1.7+esm1 | < 1.18.0-6ubuntu14.10 | < 1.24.0-2ubuntu7.7 | < 1.28.0-6ubuntu1.2
6 vendors · 9 products
