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CVE-2026-80255VulnerabilityPublished 09/06/2026Updated 10/17/2026

A Set-Cookie: header using tab (horizontal tab, ASCII code 9) instead of space (ascii code 32) immediately before the Secure attribute causes curl… (CVE-2026-80255)

Affects curlSource GCVE Database

0

Not known to be exploited · CVSS 7.5 Medium · fixed in 8.18.0-1ubuntu2.7 : update curl when convenient.

Data as of 10/25/2026, 16:58:57 UTC

CVSS 3.1 base score
7.5Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 8.18.0-1ubuntu2.7, 8.20.0-2ubuntu11
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 6 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

What to do

Affected software

ProductAffectedFixed in
Ubuntu:Pro:14.04:LTScurlpkg:deb/ubuntu/curl?arch=source&distro=esm-infra-legacy/trustyOther threatsAffected
  • =7.32.0-1ubuntu1
  • =7.33.0-1ubuntu1
  • =7.34.0-1ubuntu1
  • =7.35.0-1ubuntu1
  • =7.35.0-1ubuntu2
  • =7.35.0-1ubuntu2.1
  • =7.35.0-1ubuntu2.2
  • =7.35.0-1ubuntu2.3
  • =7.35.0-1ubuntu2.5
  • =7.35.0-1ubuntu2.6
  • =7.35.0-1ubuntu2.7
  • =7.35.0-1ubuntu2.8
  • =7.35.0-1ubuntu2.9
  • =7.35.0-1ubuntu2.10
  • =7.35.0-1ubuntu2.11
  • =7.35.0-1ubuntu2.12
  • =7.35.0-1ubuntu2.13
  • =7.35.0-1ubuntu2.14
  • =7.35.0-1ubuntu2.15
  • =7.35.0-1ubuntu2.16
  • =7.35.0-1ubuntu2.17
  • =7.35.0-1ubuntu2.19
  • =7.35.0-1ubuntu2.20
  • =7.35.0-1ubuntu2.20+esm2
  • =7.35.0-1ubuntu2.20+esm3
  • =7.35.0-1ubuntu2.20+esm4
  • =7.35.0-1ubuntu2.20+esm5
  • =7.35.0-1ubuntu2.20+esm6
  • =7.35.0-1ubuntu2.20+esm7
  • =7.35.0-1ubuntu2.20+esm8
  • =7.35.0-1ubuntu2.20+esm9
  • =7.35.0-1ubuntu2.20+esm10
  • =7.35.0-1ubuntu2.20+esm11
  • =7.35.0-1ubuntu2.20+esm12
  • =7.35.0-1ubuntu2.20+esm13
  • =7.35.0-1ubuntu2.20+esm14
  • =7.35.0-1ubuntu2.20+esm15
  • =7.35.0-1ubuntu2.20+esm16
  • =7.35.0-1ubuntu2.20+esm17
  • =7.35.0-1ubuntu2.20+esm18
  • =7.35.0-1ubuntu2.20+esm19
  • =7.35.0-1ubuntu2.20+esm20
  • =7.35.0-1ubuntu2.20+esm21
  • =7.35.0-1ubuntu2.20+esm22
Fixed in–
Ubuntu:Pro:16.04:LTScurlpkg:deb/ubuntu/curl?arch=source&distro=esm-infra-legacy/xenialOther threatsAffected
  • =7.43.0-1ubuntu2
  • =7.45.0-1ubuntu1
  • =7.46.0-1ubuntu1
  • =7.47.0-1ubuntu1
  • =7.47.0-1ubuntu2
  • =7.47.0-1ubuntu2.1
  • =7.47.0-1ubuntu2.2
  • =7.47.0-1ubuntu2.3
  • =7.47.0-1ubuntu2.4
  • =7.47.0-1ubuntu2.5
  • =7.47.0-1ubuntu2.6
  • =7.47.0-1ubuntu2.7
  • =7.47.0-1ubuntu2.8
  • =7.47.0-1ubuntu2.9
  • =7.47.0-1ubuntu2.11
  • =7.47.0-1ubuntu2.12
  • =7.47.0-1ubuntu2.13
  • =7.47.0-1ubuntu2.14
  • =7.47.0-1ubuntu2.15
  • =7.47.0-1ubuntu2.16
  • =7.47.0-1ubuntu2.18
  • =7.47.0-1ubuntu2.19
  • =7.47.0-1ubuntu2.19+esm1
  • =7.47.0-1ubuntu2.19+esm2
  • =7.47.0-1ubuntu2.19+esm3
  • =7.47.0-1ubuntu2.19+esm4
  • =7.47.0-1ubuntu2.19+esm5
  • =7.47.0-1ubuntu2.19+esm6
  • =7.47.0-1ubuntu2.19+esm7
  • =7.47.0-1ubuntu2.19+esm8
  • =7.47.0-1ubuntu2.19+esm9
  • =7.47.0-1ubuntu2.19+esm10
  • =7.47.0-1ubuntu2.19+esm11
  • =7.47.0-1ubuntu2.19+esm12
  • =7.47.0-1ubuntu2.19+esm13
  • =7.47.0-1ubuntu2.19+esm15
  • =7.47.0-1ubuntu2.19+esm16
  • =7.47.0-1ubuntu2.19+esm17
  • =7.47.0-1ubuntu2.19+esm18
Fixed in–
Ubuntu:Pro:18.04:LTScurlpkg:deb/ubuntu/curl?arch=source&distro=esm-infra/bionicOther threatsAffected
  • =7.55.1-1ubuntu2
  • =7.55.1-1ubuntu2.1
  • =7.57.0-1ubuntu1
  • =7.58.0-2ubuntu1
  • =7.58.0-2ubuntu2
  • =7.58.0-2ubuntu3
  • =7.58.0-2ubuntu3.1
  • =7.58.0-2ubuntu3.2
  • =7.58.0-2ubuntu3.3
  • =7.58.0-2ubuntu3.5
  • =7.58.0-2ubuntu3.6
  • =7.58.0-2ubuntu3.7
  • =7.58.0-2ubuntu3.8
  • =7.58.0-2ubuntu3.9
  • =7.58.0-2ubuntu3.10
  • =7.58.0-2ubuntu3.12
  • =7.58.0-2ubuntu3.13
  • =7.58.0-2ubuntu3.14
  • =7.58.0-2ubuntu3.15
  • =7.58.0-2ubuntu3.16
  • =7.58.0-2ubuntu3.17
  • =7.58.0-2ubuntu3.18
  • =7.58.0-2ubuntu3.19
  • =7.58.0-2ubuntu3.20
  • =7.58.0-2ubuntu3.21
  • =7.58.0-2ubuntu3.22
  • =7.58.0-2ubuntu3.23
  • =7.58.0-2ubuntu3.24
  • =7.58.0-2ubuntu3.24+esm1
  • =7.58.0-2ubuntu3.24+esm2
  • =7.58.0-2ubuntu3.24+esm3
  • =7.58.0-2ubuntu3.24+esm4
  • =7.58.0-2ubuntu3.24+esm5
  • =7.58.0-2ubuntu3.24+esm7
  • =7.58.0-2ubuntu3.24+esm8
  • =7.58.0-2ubuntu3.24+esm9
  • =7.58.0-2ubuntu3.24+esm10
  • =7.58.0-2ubuntu3.24+esm11
  • =7.58.0-2ubuntu3.24+esm12
Fixed in–
Ubuntu:Pro:20.04:LTScurlpkg:deb/ubuntu/curl?arch=source&distro=esm-infra/focalOther threatsAffected
  • =7.65.3-1ubuntu3
  • =7.65.3-1ubuntu4
  • =7.66.0-1ubuntu1
  • =7.67.0-2ubuntu1
  • =7.68.0-1ubuntu1
  • =7.68.0-1ubuntu2
  • =7.68.0-1ubuntu2.1
  • =7.68.0-1ubuntu2.2
  • =7.68.0-1ubuntu2.4
  • =7.68.0-1ubuntu2.5
  • =7.68.0-1ubuntu2.6
  • =7.68.0-1ubuntu2.7
  • =7.68.0-1ubuntu2.10
  • =7.68.0-1ubuntu2.11
  • =7.68.0-1ubuntu2.12
  • =7.68.0-1ubuntu2.13
  • =7.68.0-1ubuntu2.14
  • =7.68.0-1ubuntu2.15
  • =7.68.0-1ubuntu2.16
  • =7.68.0-1ubuntu2.18
  • =7.68.0-1ubuntu2.19
  • =7.68.0-1ubuntu2.20
  • =7.68.0-1ubuntu2.21
  • =7.68.0-1ubuntu2.22
  • =7.68.0-1ubuntu2.23
  • =7.68.0-1ubuntu2.24
  • =7.68.0-1ubuntu2.25
  • =7.68.0-1ubuntu2.25+esm2
  • =7.68.0-1ubuntu2.25+esm3
  • =7.68.0-1ubuntu2.25+esm4
  • =7.68.0-1ubuntu2.25+esm5
  • =7.68.0-1ubuntu2.25+esm6
  • =7.68.0-1ubuntu2.25+esm7
Fixed in–
Ubuntu:22.04:LTScurlpkg:deb/ubuntu/curl?arch=source&distro=jammyOther threatsAffected
  • =7.74.0-1.3ubuntu2
  • =7.74.0-1.3ubuntu3
  • =7.80.0-3
  • =7.81.0-1
  • =7.81.0-1ubuntu1.1
  • =7.81.0-1ubuntu1.2
  • =7.81.0-1ubuntu1.3
  • =7.81.0-1ubuntu1.4
  • =7.81.0-1ubuntu1.6
  • =7.81.0-1ubuntu1.7
  • =7.81.0-1ubuntu1.8
  • =7.81.0-1ubuntu1.10
  • =7.81.0-1ubuntu1.11
  • =7.81.0-1ubuntu1.13
  • =7.81.0-1ubuntu1.14
  • =7.81.0-1ubuntu1.15
  • =7.81.0-1ubuntu1.16
  • =7.81.0-1ubuntu1.17
  • =7.81.0-1ubuntu1.18
  • =7.81.0-1ubuntu1.19
  • =7.81.0-1ubuntu1.20
  • =7.81.0-1ubuntu1.21
  • =7.81.0-1ubuntu1.22
  • =7.81.0-1ubuntu1.23
  • =7.81.0-1ubuntu1.24
  • =7.81.0-1ubuntu1.25
  • =7.81.0-1ubuntu1.26
  • =7.81.0-1ubuntu1.27
Fixed in–
Ubuntu:24.04:LTScurlpkg:deb/ubuntu/curl?arch=source&distro=nobleOther threatsAffected
  • =8.2.1-1ubuntu3
  • =8.2.1-1ubuntu3.1
  • =8.4.0-2ubuntu1
  • =8.5.0-2ubuntu1
  • =8.5.0-2ubuntu2
  • =8.5.0-2ubuntu8
  • =8.5.0-2ubuntu9
  • =8.5.0-2ubuntu10
  • =8.5.0-2ubuntu10.1
  • =8.5.0-2ubuntu10.2
  • =8.5.0-2ubuntu10.3
  • =8.5.0-2ubuntu10.4
  • =8.5.0-2ubuntu10.5
  • =8.5.0-2ubuntu10.6
  • =8.5.0-2ubuntu10.7
  • =8.5.0-2ubuntu10.8
  • =8.5.0-2ubuntu10.9
  • =8.5.0-2ubuntu10.10
  • =8.5.0-2ubuntu10.11
  • =8.5.0-2ubuntu10.12
  • =8.5.0-2ubuntu10.13
Fixed in–
Ubuntu:26.04:LTScurlpkg:deb/ubuntu/curl?arch=source&distro=resoluteOther threatsAffected
  • <8.18.0-1ubuntu2.7
  • =8.14.1-2ubuntu1
  • =8.17.0-1ubuntu1
  • =8.18.0-1ubuntu1
  • =8.18.0-1ubuntu2
  • =8.18.0-1ubuntu2.1
  • =8.18.0-1ubuntu2.2
  • =8.18.0-1ubuntu2.3
  • =8.18.0-1ubuntu2.4
  • =8.18.0-1ubuntu2.5
Fixed in
  • 8.18.0-1ubuntu2.7
Ubuntu:26.10curlpkg:deb/ubuntu/curl?arch=source&distro=stonkingOther threatsAffected
  • <8.20.0-2ubuntu11
  • =8.18.0-1ubuntu2
  • =8.20.0-2ubuntu1
  • =8.20.0-2ubuntu3
  • =8.20.0-2ubuntu10
Fixed in
  • 8.20.0-2ubuntu11

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available and should be applied by updating curl packages to the fixed versions provided by Ubuntu. Standard system updates will include these fixes. Users should ensure their systems are updated to the patched curl versions to mitigate this issue.

Description

A vulnerability in curl causes it to improperly handle the Secure attribute in Set-Cookie headers when a horizontal tab character is used immediately before the Secure attribute instead of a space. This results in curl storing the cookie without the Secure flag, potentially causing the cookie to be sent over plaintext HTTP on subsequent requests to the same host. This issue affects specific Ubuntu package versions of curl and has a CVSS score of 7.5 (medium severity). A patch is available from Ubuntu to address this vulnerability.

Impact

Cookies that should be marked Secure may be stored without this flag, leading to their transmission over plaintext HTTP connections. This can expose sensitive cookie data to network attackers. The vulnerability does not impact integrity or availability but poses a confidentiality risk.

Summary

CVE-2026-80255 describes a flaw in curl where a Set-Cookie header using a horizontal tab (ASCII 9) instead of a space (ASCII 32) immediately before the Secure attribute causes curl to omit the Secure flag when storing the cookie. Consequently, the cookie may be transmitted over unencrypted HTTP connections, exposing sensitive information. This vulnerability affects multiple Ubuntu-specific curl package versions. Ubuntu has released patches for affected versions across various LTS releases, and standard system updates will apply the fix.

References

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